Inserting youtube videos via the editor

Added functionality to allow the insertion of video into the editor see pull request from [bootstrap-wysihtml5](https://github.com/jhollingworth/bootstrap-wysihtml5/pull/163) for more details.  

I have not been able to test change as I have never used rails before. I suggest through testing before merging into master. This commit was done at the request of @hyperrjas. 

*Commit msg:*
merged changes for video added to pull request for video to [bootstrap-wysihtml5](http://goo.gl/qB00cg) into core.js.erb