Improve user interface text.
Reverse the order of the branch selection list.
#1393858 by tim.plunkett: Clean up documentation.
#1356338: Move page callback to an include file.
#1356326: Only show the default branch menu task if it's applicable to the project.
#1356330: Put the branch name in the success message.
Fix error when the default branch is not available
Use label ids instead of check_plain()'ed branch names as keys
Otherwise there would have been the requirement to reverse check_plain()
to work with the original branch name. Thanks ECL.
Quick fix: #options of a radio widget are vulnerable against XSS
Drupal is a registered trademark of Dries Buytaert.