Mysql Patches

Created by: slifty

This PR includes a few small tweaks and fixes related to the mysql permissions setup ansible tasks.

Specifically:

• Adding mysql_root_password to the simplesaml variables template, which needs that set.
• Adding a note for which ansible version to use.
• Adding a reference to the root password to an ansible action that requires it.
• Updating permission setting actions to append permissions instead of overwrite (a quality of life improvement).

Resolves #89 (closed) Resolves #87 (closed)