Decrypt Fragments (Beta Version): Implemented and fixed layouts.

Implemented the fragments. Resolved as many bugs as i noticed. Please test it. I have little experience in android testing.  

Will do it for encryption now.

There is a small bug in messages fragment, Even If the encryption data is not valid, It calls showPassphraseDialog().

#401


![fragments-decrypt](https://f.cloud.github.com/assets/2411947/2428108/2cc1a008-ac2d-11e3-9386-0c40e5279300.png)