GitHub login fixes:

- Allow for case insensitivity in the org name list
  - Remove the check for verified email addresses when under Enterprise; it isn't supported there.

util/oauth.py

@@ -45,7 +45,11 @@ class GithubOAuthConfig(OAuthConfig):
     if not self.config.get('ORG_RESTRICT', False):
       return None
 
-    return self.config.get('ALLOWED_ORGANIZATIONS', None)
+    allowed = self.config.get('ALLOWED_ORGANIZATIONS', None)
+    if allowed is None:
+      return None
+
+    return [org.lower() for org in allowed]
 
   def _endpoint(self):
     endpoint = self.config.get('GITHUB_ENDPOINT', 'https://github.com')
@@ -53,6 +57,9 @@ class GithubOAuthConfig(OAuthConfig):
       endpoint = endpoint + '/'
     return endpoint
 
+  def is_enterprise(self):
+    return self._endpoint().find('.github.com') < 0
+
   def authorize_endpoint(self):
     return self._get_url(self._endpoint(), '/login/oauth/authorize')  + '?'
 
@@ -104,7 +111,7 @@ class GithubOAuthConfig(OAuthConfig):
 
   def validate_organization(self, organization_id, http_client):
     api_endpoint = self._api_endpoint()
-    org_endpoint = self._get_url(api_endpoint, 'orgs/%s' % organization_id)
+    org_endpoint = self._get_url(api_endpoint, 'orgs/%s' % organization_id.lower())
 
     result = http_client.get(org_endpoint,
       headers={'Accept': 'application/vnd.github.moondragon+json'},