Fix presentFromPoint and update Demo for iPhone 5

######  Fixed presentPopoverFromPoint
I did a minor change to bestArrowDirectionAndFrameFromView because a view of nil would cancel out the point passed in from presentPopoverFromPoint and set the popover to always display at 0,0.

###### Updated FPPoverDemo:
* It now works with the iPhone 5 new screen size by taking your existing startup image and carefully resizing it to the proper size.
* Added a new button "NoArrow" which displays a popover in the center of the view without an arrow.
* Now hides the navigation bar when exiting the table view.