Enabled colorbox_inline for os_files attached vids #3256

I used the inline method to attach a colorbox to a video.  Apparently that requires the colorbox_inline variable to be enabled.  It defaults to true (which is why I didn't even know we had a variable) but wasn't enabled on scholars.  The attached update hook updates teh variable.
Merge pull request #3346 from openscholar/3256-colorbox_inline

Enabled colorbox_inline for os_files attached vids #3256