Display a warning prompt in presubmit if the tree status is in 'Caution'.

Example presubmit output:


Running presubmit upload checks ...

** Presubmit Warnings **
Tree state is: caution

***************
Please use caution in checkins
http://skia-tree-status-staging.appspot.com/banner-status?format=json
***************

There were presubmit warnings. Are you sure you wish to continue? (y/N):
Review URL: https://codereview.appspot.com/7200043

git-svn-id: http://skia.googlecode.com/svn/trunk@7337 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed