Puts PlaceController in the business of showing the user
"Are you sure" prompts on place change cancellation, per
Thomas Broyer's suggestion

http://groups.google.com/group/google-web-toolkit-contributors/browse_thread/thread/7d96ce234abe67cd

This is the only generalized way I can see to keep the user from
losing changes on window close, etc.

Review at http://gwt-code-reviews.appspot.com/698801

Review by: robertvawter@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8386 8db76d5a-ed1c-0410-87a9-c151d255dfc7
11 files changed