Properly encode URLs passed to github contents endpoint

- This fixes a bug where a URL could come in with 2 '?'.  We'd pass that down
  to the github API, and it would be ignored by the API.  Then, the API would
  return a different return type that expected in
  rendered_markdown_from_github.
- Now these URLs will return a 404 because the requested guide can not be
  found.  In addition, this will allow us to support guides with special URL
  characters in them now like '?'.
- To reproduce and test see below.

- For example, request this URL:
    - /front-end-javascript/introduction-to-test-driven-development-in-javascript?status=in-review?branch=adityavarshney
- This would result in us passing the following 'path' to the github contents
  API:
    - repos/durden/articles/contents/in-review?branch=adityavarshney/front-end-javascript/introduction-to-test-driven-development-in-javascript/article.md
- This would in turn return the contents of the contents/in-review/ directory,
  not a single file.  This would finally result in a TypeError because the
  response was not text, but a list of values for each file in the directory.

pskb_website/remote.py

@@ -5,6 +5,7 @@
 import base64
 import collections
 import json
+import urllib
 
 from flask_oauthlib.client import OAuth
 from flask import session
@@ -269,7 +270,7 @@ def read_file_from_github(path, branch=u'master', rendered_text=True,
         # seems like a safe enough bet at this point.
         owner, repo, file_path = split_full_file_path(path)
         url = u'https://github.com/%s/%s/blob/%s/%s' % (owner, repo, branch,
-                                                        file_path)
+                                                        urllib.pathname2url(file_path))
 
         details = file_details(path, branch, None, None, url, text)
     else:
@@ -295,11 +296,7 @@ def rendered_markdown_from_github(path, branch=u'master', allow_404=False):
 
     resp = github.get(url, headers=headers, data={'ref': branch})
     if resp.status == 200:
-        try:
-            return unicode(resp.data, encoding='utf-8')
-        except TypeError:
-            app.logger.error('Failed parsing response, url: "%s", branch: "%s"', url, branch)
-            raise
+        return unicode(resp.data, encoding='utf-8')
 
     if resp.status != 404 or not allow_404:
         log_error('Failed reading rendered markdown', url, resp, branch=branch)
@@ -517,7 +514,8 @@ def contents_url_from_path(path):
     """
 
     owner, repo, file_path = split_full_file_path(path)
-    return 'repos/%s/%s/contents/%s' % (owner, repo, file_path)
+    return urllib.pathname2url('repos/%s/%s/contents/%s' % (owner, repo,
+                                                            file_path))
 
 
 def read_branch(repo_path, name):