MySQL: Installation and basic configuration

This script implements the section "Database -> Controller setup" of the
OpenStack install-guide for Icehouse/Ubuntu.

It installs the MySQL server package and the Python library, sets the
database root password as configured in the credentials config file,
and edits my.cnf as described in the manual. -- This part shows how
devstack functions can be used to edit configuration files.

Note that mysql_secure_installation (from the manual) is not called
because the option that made it work for unattended installs didn't make
it into the version of MySQL that is in Ubuntu 12.04 LTS.

Partial-Bug: 1312764
Implements: blueprint openstack-training-labs
Change-Id: I4d40b84a18d42572214137fb664ffb514fee6ef9
Merge "MySQL: Installation and basic configuration"