fix an issue where leaving the app & coming back in would ignore keyboard

i have run into a problem whereby, when the FPPopoverController's context is a ViewController controlling a textView, leaving the app and then coming back in causes the FPTouchView to respond to touches on the keyboard because it would call the outsideBlock() which dismisses the popover.

this change just sets the first-responder chain, and so if the content VC has a firstResponder, it will help FPTouchView skip the dismiss call.