Let travis hook be called on Failed/Passed/Started builds

Because in Travis configuration file one can configure when webhook notification is invoked, I find it more flexible allowing hubot travis script to react on ANY builds notifications from Travis CI.

For example, our team wanted to receive notifications via Hubot on both failed and passed builds in chat room. The change I made allows travis script to just blindly report what Travis notification just passed to it, I think this is the way it should behave.

Hope this makes sense