Allow selectively disabling resource controls on index view.

[MrJoy]

Currently the only way to do this is via permissions, but it would be nice if we could selectively disable these generally for a given model.

In particular, if I'm using link_to_resource, then a button for show is just wasted space.

[adrianthedev]

I know and I'd like to handle that in a greater refactor where you could more easily customize the actions shown on each row. Maybe even collapse the buttons under a single button somehow.