Change root password feature + Vagrant testing tools

[farridav]

• Add in Vagrantfile for easy testing and contributing
• Ensure we do an idempotence test in travis
• Provide a way to change the root password and document it

Fixes https://github.com/ANXS/mysql/issues/23

[otakup0pe]

I was able to use this functionality to change the root password so that's pretty :cool: