Checking events when looking for existing webhooks
Checking events when looking for existing webhooks

This logic only used to check the webhook URL, but the events for that
URL might not be the events this server wants. Now it also ensures all
required events are included, and if not, will create a new webhook.

brev/nupic.tools,numenta/nupic.tools,rhyolight/nupic.tools,numenta/nupic.tools,rhyolight/nupic.tools,brev/nupic.tools