small screen height correction to stop overscroll on iOS
This is a slightly kludgy way to stop the annoying 1px pre and post
transition jumps caused by screen scrolling on, at least, iOS. Basically
setting this causes defaultHomeScroll to be set to 0 deep within JQM and
hence the scrollPage function in transitions to do nothing. Without this
defaultHomeScroll is set to 1 and scrollPage scrolls the page 1px