ISU-98 Remove wysiwyg dependency. Add ckeditor hook to enable for ckeditor.

Copy the media_crop plugin to have a specific version for ckeditor. Hook into
ckeditor so that media_crop can be used with ckeditor OR wysiwyg.
ISU-98 Fix undefined index error with missing attributes.

Sometimes media_crop them function does not receive all the attributes
it's expecting. This adds a check to make sure the attribute exists
before trying to use it.
Merge pull request #2 from kevinchampion/ckeditor

Remove wysiwyg dependency. Add ckeditor hook to enable for ckeditor