Changed the appNetUser property of XIGUserMatcher to not be a signal anymore.

The appNetUser property is now instead computed before the
XIGUserMatcher creation. This makes the processing of the XIGUserMatcher
much easier in the tableview cells.
Add FilterViewController displayed at the bottom of the Friends screen.

The Friends screen re-uses the Semi-modal view controller to display
both the TwitterUsersTableVC and the FilterVC.
Resize Friends screen tableview to not be behind the filter bar.

It is much easier to resize the tableview in code, I hence deleted
the XIB and build view hierarchy in code as it is very simple.
updated ReactiveCocoa