Move away from MySQL to MariaDB

[mtangoo]

MySQL libraries are GPLed. MariaDB connectors are LGPLed.
Move off GPL towards LGPL is the goal of this issue.

[mtangoo]

I'm testing for both libraries but definitely future "official" test will be done against MariaDB.
Testing for MySQL is welcome

[mtangoo]

Since MySQL and MariaDB seems to move apart with each release, remove all reference to MySQL so that when MariaDB client library aren't supported by MySQL there wont be an issue. Mention this on Readme