Edit screen tab order

Hi Boone-

Here's a quick fix for the tab order problem on the docs edit screen. I added another bit to the MCE init callback to add tab order attributes to the MCE toolbar buttons. Again, only the most recent commit is of interest: https://github.com/dcavins/buddypress-docs/commit/6b92cac83faa16f6f6561e27ad80a905a7c3fd30

I noticed that it was a problem in the text editor mode only (visual editor mode was fine) which led to this similar sounding issue: http://core.trac.wordpress.org/ticket/20834

I'm sure there's more than one way to fix the problem. (Also, I appreciated your post: http://teleogistic.net/2012/02/using-init-callbacks-with-tinymce-and-wp_editor-in-wordpress/ )

-David