Updated error module to be more efficient.

Now only listens to error publications that correspond to the current loglevel

Added loglevel changing method to help facilitate this. Updates error.loglevel, and publishes
the new log level. A new loglevelChyanged subscription then unsubscribes current error
subscriptions, and resubscribes to publications that meet the new loglevel.

TODO: Needs error checking to make sure that the new loglevel is valid