Role Manager: Enhance capability management

[JoryHogeveen]

1.7.3:

• Show custom capabilities that are not stored but only active in a caps view (use filter from compat class)

Todo:
Cap storage:

• Allow storage of caps that are not used by any roles and are not added by other plugins.
• Allow removal of these caps when they are stored by this module
  • If they are removed but a plugin is added (or anything) that uses this cap it will still show up but the remove option will not be available