Not all entities have bundle keys

Further to the patch we committed yesterday (#1421666: The "modify entity values" action should respect the views bundle filter if it exists), we are assuming that all entities will return a 'bundle key', but users, comments, files etc... don't have this in their entity info. This patch Just checks if it's there first, then sets, otherwise false. Then also checks if there is a bundle key before looking in the view.

Patch arriving shortly.