Generic monitor and mail template and tasks revamp.

tasks/main.yml:
- Split into several task files.

task/monitors.yml:
- Now saves monitors on monitrc.d instead of conf.d.

templates/mail.j2:
- Now templating mail configs onto /etc/monit/conf.d/mail.
Added defaults for monit_mailserver_host and _port.
Updated README.md.
Deleted deprecated monitor templates.
Testing with vagrant.
Filled galaxy meta info.
Fix issue #9: this role no longer creates groups.