updated twitteroauth library to latest from github: https://github.com/abraham/twitteroauth/commit/61f5a550cd3643c619e84cb914ef1f22e491c270 (note: now conflicts with oauth_api library)
centralize the creation of the api object
Fixes #4917 Using twitter API v1.1
removes oauth plugin as twitter_api does not depend on it anymore
Merge pull request #5360 from cash/twitter1.1

Twitter API 1.1 update