Improve messages in Maze.  Create common CSS file for apps.  Make OK buttons blue.

R=spertus@google.com

Review URL: https://codereview.appspot.com/12782044

git-svn-id: http://blockly.googlecode.com/svn/trunk@1228 c400ca83-b69d-9dd7-9705-49c6b8615e23