Allow service to not be controlled by Puppet

Change the ensure => "present" state to not create the "service" resource. Which leaves the service uncontrolled by Puppet, and allows to be not controlled by Puppet.

ensure => "present": Create config and don't control service
ensure => "running", ensure => "stopped": Create config and service with given ensure state.
ensure => "absent": Stop service and remove config

The downside is that it changes the behavior of the default "present" state. I also changed the default state to "running" to preserve default behavior. For compatibility, it might make sense to leave behavior of "present" unchanged and create a new state for the uncontrolled behavior. 

This is an implementation of feature proposed in #76.