refs #257: add link capability in cli
fixes #255: restart policy support
added extension ; basic api control
extension management with api and cli
more logging for extensions
fixed extension config parse bug
added registration action for extensions
added config prompts for extensions
added cleanup for extension containers upon extension removal
check for env when registering extension
more volume updates; update for nameless args
added container name and volumesFrom options for extensions
added health check and recovery for extensions
remove VolumesFrom