Add missing variables in 'monit' role
Add test sshd_config test before sshd restart

This should prevent accidental lock-outs when sshd configuration has
a problem and sshd daemon won't restart because of that.

Fixes #152.
Update 'mysql' role dependencies

Configuration of firewall and tcpwrappers access to MySQL server is
moved from the 'mysql' role itself to dependencies ('ferm' and
'tcpwrappers', respectively).

Fixes #155.
Merge pull request #157 from drybjed/bugfixes

Small bugfixes in three roles