Removed extraneous debug references. Clustering is now fully-supported with 3+ nodes. Slight modification to default directory permissions, and default influxdb configuration file.

Updated clustering logic to add 3+ nodes. Added a few more checks to ensure clustering is successful (and fail if not).

Added is_vagrant variable, modified defaults file to modify logic depending on whether running on vagrant.

Added extra flag to control whether InfluxDB should be started on install. Templates use 'influxdb' group when joining cluster, so all influxdb instances that need to be clustered must be part of that group (previously it was using all hosts).