Grantinee revokes permissions multiple times for each user

[JohnBDonner]

Because we are revoking for every permission for each user, we should probably refactor this so that we only revoke once per user.

I, [2018-06-14T09:21:27.303598 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.304487 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.304525 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.305391 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.305427 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.306258 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.306294 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.307137 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.307179 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.308099 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.308136 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.308995 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.309031 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.309876 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
I, [2018-06-14T09:21:27.309917 #30]  INFO -- : REVOKE ALL PRIVILEGES ON `database`.* FROM 'some_dude'@'<<host>>';
D, [2018-06-14T09:21:27.310758 #30] DEBUG -- : User some_dude@<<host>> doesn't have any grants yet
...

Not a big issue, but redundant 😃

[pawelkomarnicki]

We could filter and select uniq combinations from the DSL's @permissions array :-)