Added support for using different versions of Facebook SDK
Added a function to check what version of Graph API is being used.
Added tests for using different versions of the Graph API
Code is now PEP 8 compliant.
Removed extra '/' from version. Adding new api versions now only involves one line change
Tests now rely on an app access token created with the app ID/secret enviroment variables instead of relying on another access token enviroment variable
Removed setUp method entirely from tests because no access token is necessary to run tests
Merge pull request #158 from jeffreychan637/master

Add support for Graph API versionoing - see https://developers.facebook.com/docs/apps/versions. Fix #142.