Improve consistency of quota checking in forms

Add quota based validations to floating_ips and instance forms. Unify
the implementation of disabled/enabled button for instance and
floating_ips table. Add disabled/enalbed button to volumes table.

Change-Id: I488e86e467369f35244bdcd34ecaaee32e56ba2d
fixes: bug #1070899
Merge "Improve consistency of quota checking in forms"