Feature 2307 - Include ::daemon or ::cron classes based on runmode param value

Updated code to add a 'runmode' param which can be used to set Puppet agent up as using ::Cron or ::daemon classes based on value. 

* New Param added - runmode. Defaults to 'service'. 
* Runmode param added to init.pp
* Config.pp updated with a case statement to include relevant class based on runmode value. Fail for any unsupported values.