Fix bug where access token calls fail w/ version.

When an version was applied to the GraphAPI object, access token calls
would fail (because the "oauth/access_token" endpoint does not use a
version).

Fix bug by removing version from the request method and manually
applying it to the specific methods that need it.
Fix #161.

Fix regression described in #161 by adding a default API version to all
calls.

Note that while the default version is 1.0, Facebook will automatically
coerce API calls to later versions for newer applications that are
unable to access this version.
Fix #131.

Thanks @dvolgyes for reporting this.
Fix multiple regressions.

Fix regressions related to versioning and FQL.