Add assignment suggestions

[thequbit]

Feedback from WXXI:

Add assignment, question, story suggestion assignment to drive interest in use that lets moderator(s) respond to issues the audience cares most about.

Add ability to 'suggest an assignment' back to moderators. This could just be a button on the top of the HomeActivity.

[thequbit]

This is up for debate on the best way to implement this. I think from a UI stand point we may need to think out how the fragment looks for viewing an assignment, and not directly go to the post fragment.