Fix mysql-community-server install (fixes #2)

This sets up the mysql yum repo so the mysql-community-* packages can be installed.

r? @jasonthomas 

I've add a new module dir for cheesecake because I'm thinking that might be useful for defining the bits specific to utilizing the other puppet modules for this project.

Let me know if you have any thoughts re: better layout etc.

To test this I ran `vagrant destroy && vagrant up` (Be sure there's nothing you want to keep in the existing image before you do that).