Use lsyncd's status log for calculating inotify watches.

The current method of calculating inotify watches can be intensive.  It also requires the configuration file use source="/path/on/disk" otherwise it fails to correctly pick up directories.

Lsyncd makes this information avialable to us in it's status file, so this update defaults to that and will fall back to the other method.
Should this `exit 1`? Seems like an error if you are using this plugin and it unexpectedly missing.