Crop "lightbox" issues

[meszarosrob]

z-index problems with "add media", "visual", "text" buttons, and sidebar.

also when i have a narrow long crop I can't access anymore the action buttons

see screenshot here: https://www.dropbox.com/s/qt16nzex396jhqi/Screenshot%202014-04-19%2014.48.47.png

[andersthorborg]

Thanks again, @meszarosrob!

Closed in #10