Changed dependancy of cancan

cancan has been depreciated for cancancan, updated gem spec to reflect
this.
bundle updated
Merge branch 'ssilvius-master'
lock current version to use comfy version 1.12.2
add abort link to content edit page manually
reinclude the status button next to the revisions button
open the preview in a new page / tab
remove not existing javascript cms_fortress.js
logout route is listening to GET and not DELETE
upgraded to aasm 4