Allow pillars for minions to be retrieved from MySQL

I noticed we didn't have a Pillar module to retrieve data by running a simple MySQL query so I decided to write one.

There already is a Django ORM one that allows you to retrieve data from databases but this may be too complicated for setups where you'd simply want to pull (basic) Pillar data from MySQL to make it easier to work with (edit, overview) etc.

I'm open to suggestions and feel free to add/improve as you see fit!