Explicitly set pro version ad width to prevent it from wrapping in Chrome.

git-svn-id: https://plugins.svn.wordpress.org/admin-menu-editor/trunk@818849 b8457f37-d9ea-0310-8a92-e5e31aec5664
Increase button width to prevent button text from being cut off in WP 3.8+.

git-svn-id: https://plugins.svn.wordpress.org/admin-menu-editor/trunk@818850 b8457f37-d9ea-0310-8a92-e5e31aec5664