Add WYSIWYG editor to admin section

[mutantmonkey]

This should be easier for people less well-versed in markdown. The question is if we can find one that's light enough for us to use.

[echarlie]

Perhaps we should use a more interactive WYSIWYM editor, like the one here on github, which inserts the appropriate markdown using an interface people expect, but doesn't render it.

[paulwalko]

ocvt uses tinymce