change to use mysql instead of sqlite

This change has a matching branch in ansible-dev HydraNorth.mysql.
```
hg clone https://code.library.ualberta.ca/hg/ansible-dev/
cd ansible-dev
hg checkout HydraNorth.mysql
```

* replaces sqlite with mysql
* playbook requires ansible-vault password (see PasswordSafe)
* hint: create a ```.vault_pass.txt``` containing just the password to continue using ```vagrant up hydranorth```