Adds plist resource

This makes it possible to write plist files from node attributes.
It will automatically convert the hash to the plist XML format using
the plist gem. It will restart the plist when it has changed.
This means this should only be used for LaunchAgents or LauncDaemons.
[subliminal] Adds support for LaunchAgents
[TODO] Removes Plex Media Center
[TODO] Updates Plex Media Server
[plex_media_server] Adds settings
[doxie] Updates to v2.4.0
[sabnzbd] Updates to v0.7.16