Transform github repo url into website url
If a website's github repo is https://github.com/barack_obama/2016-01-01-whitehouse then we know the website is https://barack_obama.github.io/2016-01-01-whitehouse

When using the "Import" or "Update from URL" it requires the _website_ rather than the _repo_.  However, if given the repo, can't we have AMY transform the URL into a valid website URL?  

Often I get a repo url from an instructor (esp. for self organized) workshops and I manually do that transformation myself.

diff --git a/workshops/test/test_util.py b/workshops/test/test_util.py
index 35a4796f..eae27459 100644
--- a/workshops/test/test_util.py
+++ b/workshops/test/test_util.py
@@ -99,6 +99,8 @@ Other content.
             'http://swcarpentry.github.io/workshop-template',
             'https://swcarpentry.github.com/workshop-template',
             'http://swcarpentry.github.com/workshop-template/',
+            'http://github.com/swcarpentry/workshop-template',
+            'https://github.com/swcarpentry/workshop-template',
         ]
         expected_url = ('https://raw.githubusercontent.com/swcarpentry/'
                         'workshop-template/gh-pages/index.html')
diff --git a/workshops/util.py b/workshops/util.py
index 142cfb16..77b14ed6 100644
--- a/workshops/util.py
+++ b/workshops/util.py
@@ -473,8 +473,7 @@ class WrongWorkshopURL(ValueError):
     (see `generate_url_to_event_index` below)."""
 
     def __str__(self):
-        return ('Event\\'s URL doesn\\'t match Github website format '
-                '"http://user.github.io/2015-12-08-workshop".')
+        return 'Event\\'s URL doesn\\'t match Github website or repo format.'
 
 
 def generate_url_to_event_index(website_url):
@@ -482,11 +481,11 @@ def generate_url_to_event_index(website_url):
     file in GitHub repository."""
     template = ('https://raw.githubusercontent.com/{name}/{repo}'
                 '/gh-pages/index.html')
-    regex = Event.WEBSITE_REGEX
 
-    results = regex.match(website_url)
-    if results:
-        return template.format(**results.groupdict()), results.group('repo')
+    for regex in [Event.WEBSITE_REGEX, Event.REPO_REGEX]:
+        results = regex.match(website_url)
+        if results:
+            return template.format(**results.groupdict()), results.group('repo')
     raise WrongWorkshopURL()
 
 
['workshops/util.py', 'workshops/test/test_util.py']