Move CI install to install & add verbosity

Author: clavin

.travis.yml

@@ -17,4 +17,4 @@ after_success:
 # by the `env` specified in the matrix. That lets us test against
 # multiple Hubot versions. This is a bit messy, but works around
 # package.json only being able to specify one version.
-script: npm install && npm install hubot@"$HUBOT_VERSION" && npm test
+install: npm install && npm install -dd hubot@"$HUBOT_VERSION"