Listbuildsbystatus

This includes the code from PR #3 Should fix #1 #2 #3 

Given the projects setup under the HUBOT_CIRCLECI_TOKEN you supply, this new feature will iterate over all projects (one API call, not many) and then pull the most recent build status for the default_branch configured in CircleCI. Then, depending on if you say `list failed` or `list success`, it will output the appropriate information for the projects that match that status.