Sets the maximumNumberOfTouches on the panGestureRecognizer to be as many touches as the gesture started with for the duration of the gesture.

This fixes a problem where the keyboard jumps around erratically if you start panning down to dismiss with one finger, and then touch the keyboard with a 2nd finger as it is being scrolled off the screen.
Merge pull request #28 from ehopealot/fix-touch-while-dismissing

Sets the maximumNumberOfTouches on the panGestureRecognizer to be as man...