liniting main class, moving key() to seperate class

The removal of  `  $configdir = '/etc/backup.d',` was because this parameter was specified twice in the main class.

See merge request !6

* Default nagios service name changed to "backups-${name}"
* Fix checkbackups cronjob command
* Add parameters for checkbackups warn/crit levels
* Update upgrade notice

Conflicts:
	README

See merge request !5

March2015 refactor

This branch is an attempt to bring the backupninja module in the 21st century. See the upgrade notice in the README for details.

See merge request !4

we still have a somewhat fucked up structure here, but that's how we use it at koumbit right now