Minor rendering bug for clickable `docs serve` output
### Describe the bug

When running `dbt serve` the printout of the url where the docs are served is rendering with a period ('.') immediately adjacent to the link. This is a minor issue but it prevents link detection from working correctly by terminals (VS Code in my case) which automatically detect URLs and render them as hyperlinks. In this case, the output is correctly parsed as a URL but because the URL includes a '.' at the end, it reaches a dead end (equivalent to pasting `http://localhost:8081.` in chrome address bar).

```
To access from your browser, navigate to http://localhost:8080.
```

### Steps To Reproduce

1. Run `dbt docs serve`

### Expected behavior

Ideally, the printout would be rendered as:

```
To access from your browser, navigate to: http://localhost:8080
```

### Screenshots and log output

```
Running with dbt=0.13.0
Serving docs at 0.0.0.0:8080
To access from your browser, navigate to http://localhost:8080.
Press Ctrl+C to exit.
```

### System information
**Which database are you using dbt with?**
- [ ] postgres
- [ ] redshift
- [ ] bigquery
- [ ] snowflake
- [ ] other (specify: ____________)


**The output of `dbt --version`:**
```
Running with dbt=0.13.0
```

**The operating system you're using:**

**The output of `python --version`:**

### Additional context
Add any other context about the problem here.

diff --git a/core/dbt/task/serve.py b/core/dbt/task/serve.py
index d92f37312..2170d00e5 100644
--- a/core/dbt/task/serve.py
+++ b/core/dbt/task/serve.py
@@ -20,7 +20,7 @@ class ServeTask(ProjectOnlyTask):
 
         logger.info("Serving docs at 0.0.0.0:{}".format(port))
         logger.info(
-            "To access from your browser, navigate to http://localhost:{}."
+            "To access from your browser, navigate to:  http://localhost:{}"
             .format(port)
         )
         logger.info("Press Ctrl+C to exit.\\n\\n")
['core/dbt/task/serve.py']