Cleanup for permissions assigned to 'all':

* When granting or revoking, treat 'all' as a group
* Fix typo that prevented revocation from working for 'all'
* Update accumulate_grants/2 to pull grants assigned to 'all'
* Block admins from using 'all' as a user or group

Ancillary change, but useful for verifying above and for admins:

* Display grants to a group or user separate from inherited
Add eunit tests
Port dialyzer warning fixes from #528.
Fix some more dialyzer warnings.

riak_core_console:

* del_source/2 and add_grant/3 always returns 'ok'.
* Make sure that parse_cidr/1 and parse_options() match up with the
  types expected from riak_core_security.

riak_core_security:

* add_grant/3 and add_revoke/3 accept 'any' as a bucket name.
* add_source/4 uses Source as an atom.