Add remote url query modifications

* Add additional remote url beginning query
* Add additional remote url ending query
* Open files and commits using http instead of https (more generalized)
Merge branch 'issue/remote_url_query_additions'
Verify GitHub URL reachability prior to opening a file or commit
Merge branch 'issue/verify_url_reachability'
Fix comments.
Fix error check for "sendSynchronousRequest:returningResponse:error".

See documentation:
"Return Value: The downloaded data for the URL request. Returns nil if a connection could not be created or if the download fails."
Use HTTP protocol if HTTPS is not available (possible in Github on premise solutions).

On the first request a HEAD request is made against the HTTPS URL. If this works, HTTPS is used by default without further checks. If this doesn't work, HTTP is used and the check is performed on every subsequent request (until HTTPS is detected).
Add Git Merge 2013 link.