Twit 03 view pager and fragments

Creates a view pager and migrates all activities to fragments. Authentication Manager has been refactored into the authentication fragment, to prevent lots callbacks.

![authenticationmenu](https://cloud.githubusercontent.com/assets/3380092/3855378/e9be7c2a-1ee3-11e4-9897-3c9a07d58463.png)
![viewpager](https://cloud.githubusercontent.com/assets/3380092/3855384/f066ba2e-1ee3-11e4-8124-92af39a6d7b8.png)

![screen shot 2014-08-08 at 14 04 31](https://cloud.githubusercontent.com/assets/3380092/3856820/b7adc75e-1efc-11e4-8810-1546d535a580.png)

Creates a shadow around each of the tweet list items. I wasn't sure what to call each of the colours so I settled for this :tongue: