incompatible with Ubuntu 16.04

Hey, i tried this role on Utuntu 16.04. It just incompatible like described in #49. Your fix doesn't solve the issue because it wasn't an extra PPA, it is the default package wich contains mysql 5.7.

AFAIK it is not that easy to get the Version of an installed package. So i prefer to remove the deprecated options, and if needed, to make them optionally available. 
