Summary: The touch-retention offset defines a rect around a touchable component in which the touch is retained. Easiest way to see this is to touch a button in a real navigation bar and slide your finger out of the range and back in. This diff exposes the offset as a prop (I thought touchRetentionOffset was a more informative name than pressRectOffset)
Fixes#198
Closes https://github.com/facebook/react-native/pull/713
Reviewed By: svcscm
Differential Revision: D2115370
Pulled By: shayne
fb-gh-sync-id: c3f57940dfa3806f9c88df03a01d4d65bb58cf32
f331d2a844