Adding Fragments for Mentions and User profile.

User can switch between Timeline and Mention views using tabs.
User can view their home timeline tweets.
User can view the recent mentions of their username.
User can scroll to bottom of either of these lists and new tweets will load ("infinite scroll")
User can navigate to view their own profile
User can see picture, tagline, # of followers, # of following, and tweets on their profile.
User can click on the profile image in any tweet to see another user's profile.
User can see picture, tagline, # of followers, # of following, and tweets of clicked user.
Profile view should include that user's timeline
Merge branch 'master' of https://github.com/jaiminshah/SimpleTwitterClient