remove unused options and rename method for clarity
change plugin init and remove plugin bot params

* change init order so that init will always run before any event
  code is fired on plugins.  This avoids having to use join with
  a started test just to guard against :firehose events running
  before / during init.
* no need for bot param anywhwere since plugins have access to the
  bot from their instance scope via the bot method.
Merge pull request #15 from tykeal/remove-bot-from-pubsub-args

refactor plugin init and remove bot from events