CLEANUP remove unused import and commented out code
CLDCONNECT-665 get token expiration from 'expires' instead of 'expires_in'

Even though the OAuth2 specification says it should be called expires_in (http://tools.ietf.org/html/draft-ietf-oauth-v2-05#section-3.5.2), Facebook uses the expires param (https://developers.facebook.com/blog/post/2011/05/13/how-to--handle-expired-access-tokens/)