Add "Open [in Awful Browser]" option when tapping a homepage in a user profile.

Bonus: DRY up opening an Awful Browser.
Only add "Close" or "Done" button to presented views if they're alone in their navigation controllers.

Sometimes presented views get other views pushed into their navigation
controller, and we don't want to remove the back button.
Resolve tapped link URLs within AwfulPostsView.
Formatting and redundancy elimination.