Embulk 0.8.28 and 0.8.29 doesn't work Liquid {% include %}.
## Summary

Embulk 0.8.29 doesn't work liquid.  {% include %}
The following configuration works fine on 0.8.18, but It doesn't work on 0.8.19.

## Expect behavior

* Embulk 0.8.18

```
embulk preview config.yml.liquid
2017-08-10 12:53:43.210 +0900: Embulk v0.8.18
2017-08-10 12:53:44.502 +0900 [INFO] (0001:preview): Listing local files at directory '/private/tmp/hoge/csv' filtering filename by prefix 'sample_'
2017-08-10 12:53:44.506 +0900 [INFO] (0001:preview): Loading files [/private/tmp/hoge/csv/sample_01.csv.gz]
+---------+--------------+-------------------------+-------------------------+----------------------------+
| id:long | account:long |          time:timestamp |      purchase:timestamp |             comment:string |
+---------+--------------+-------------------------+-------------------------+----------------------------+
|       1 |       32,864 | 2015-01-27 19:23:49 UTC | 2015-01-27 00:00:00 UTC |                     embulk |
|       2 |       14,824 | 2015-01-27 19:01:23 UTC | 2015-01-27 00:00:00 UTC |               embulk jruby |
|       3 |       27,559 | 2015-01-28 02:20:02 UTC | 2015-01-28 00:00:00 UTC | Embulk "csv" parser plugin |
|       4 |       11,270 | 2015-01-29 11:54:36 UTC | 2015-01-29 00:00:00 UTC |                            |
+---------+--------------+-------------------------+-------------------------+----------------------------+
```

### Actual behavior

* Embulk 0.8.29

```
embulk selfupdate
2017-08-10 12:54:10.851 +0900: Embulk v0.8.18
Checking the latest version...
Found new version 0.8.29.
Downloading https://dl.bintray.com/embulk/maven/embulk-0.8.29.jar ...
Embulk::VERSION in (J)Ruby is deprecated. Use org.embulk.EmbulkVersion::VERSION instead. If this message is from a plugin, please tell this to the author of the plugin!
Updated to 0.8.29.
```

```
embulk preview config.yml.liquid
2017-08-10 12:54:37.897 +0900: Embulk v0.8.29
org.embulk.config.ConfigException: com.fasterxml.jackson.databind.JsonMappingException: Field 'in' is required but not set
 at [Source: N/A; line: -1, column: -1]
	at org.embulk.config.ModelManager.readObjectWithConfigSerDe(ModelManager.java:75)
	at org.embulk.config.DataSourceImpl.loadConfig(DataSourceImpl.java:220)
	at org.embulk.exec.PreviewExecutor.doPreview(PreviewExecutor.java:104)
	at org.embulk.exec.PreviewExecutor.access$000(PreviewExecutor.java:31)
	at org.embulk.exec.PreviewExecutor$1.run(PreviewExecutor.java:83)
	at org.embulk.exec.PreviewExecutor$1.run(PreviewExecutor.java:79)
	at org.embulk.spi.Exec.doWith(Exec.java:25)
	at org.embulk.exec.PreviewExecutor.preview(PreviewExecutor.java:79)
	at org.embulk.EmbulkEmbed.preview(EmbulkEmbed.java:169)
	at org.embulk.EmbulkRunner.previewInternal(EmbulkRunner.java:242)
	at org.embulk.EmbulkRunner.preview(EmbulkRunner.java:118)
	at org.embulk.cli.EmbulkRun.runSubcommand(EmbulkRun.java:469)
	at org.embulk.cli.EmbulkRun.run(EmbulkRun.java:100)
	at org.embulk.cli.EmbulkBundle.checkBundleWithEmbulkVersion(EmbulkBundle.java:42)
	at org.embulk.cli.EmbulkBundle.checkBundle(EmbulkBundle.java:15)
	at org.embulk.cli.Main.main(Main.java:26)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Field 'in' is required but not set
 at [Source: N/A; line: -1, column: -1]
	at org.embulk.config.TaskSerDe$TaskDeserializer.deserialize(TaskSerDe.java:181)
	at com.fasterxml.jackson.databind.ObjectMapper._readValue(ObjectMapper.java:3708)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2005)
	at org.embulk.config.ModelManager.readObjectWithConfigSerDe(ModelManager.java:72)
	... 15 more

Error: com.fasterxml.jackson.databind.JsonMappingException: Field 'in' is required but not set
 at [Source: N/A; line: -1, column: -1]
```

### configuration

config.yml.liquid

```
{% include 'commons/test' %}
out: {type: stdout}
```

commons/_test.yml.liquid

```yaml
#
in:
  type: file
  path_prefix: /private/tmp/hoge/csv/sample_
  decoders:
  - {type: gzip}
  parser:
    charset: UTF-8
    newline: LF
    type: csv
    delimiter: ','
    quote: '"'
    escape: '"'
    null_string: 'NULL'
    trim_if_not_quoted: false
    skip_header_lines: 1
    allow_extra_columns: false
    allow_optional_columns: false
    columns:
    - {name: id, type: long}
    - {name: account, type: long}
    - {name: time, type: timestamp, format: '%Y-%m-%d %H:%M:%S'}
    - {name: purchase, type: timestamp, format: '%Y%m%d'}
    - {name: comment, type: string}
```

diff --git a/embulk-core/src/main/java/org/embulk/EmbulkRunner.java b/embulk-core/src/main/java/org/embulk/EmbulkRunner.java
index 1b418f0b..cc64ca54 100644
--- a/embulk-core/src/main/java/org/embulk/EmbulkRunner.java
+++ b/embulk-core/src/main/java/org/embulk/EmbulkRunner.java
@@ -417,7 +417,9 @@ public class EmbulkRunner
             return this.embed.newConfigLoader().fromYamlString(
                 runLiquid(new String(Files.readAllBytes(configFilePath), StandardCharsets.UTF_8),
                           templateParams,
-                          templateIncludePath));
+                          (templateIncludePath == null
+                           ? configFilePath.toAbsolutePath().getParent().toString()
+                           : templateIncludePath)));
         }
         else if (EXT_YAML.matcher(configFilePath.toString()).matches()) {
             return this.embed.newConfigLoader().fromYamlString(
['embulk-core/src/main/java/org/embulk/EmbulkRunner.java']