Pivotal 67046576: enable sharing of bounce - on new last level

Added a freePlay level to bounce.
Copied sharing code and strings from flappy to bounce.
Changed makeYourOwn.html.ejs to substitute variables to it can be shared.

Fixed sharing button height for flappy and bounce to match the buttons nearby.
Removed the 1-pixel square and 1-pixel border around the visualization area for bounce/flappy. This results in zero horizontal scrolling on the phone width (400px) mobile share page.