gcm callback should have two parameters

Because of the missing parameter, multicastResult was not processed
correctly
More verbose logging support using winston
Merge pull request #20 from futurice/auth

HTTP authentication support for running pushd in the cloud
Merge pull request #19 from futurice/logging

More verbose logging support using winston
Merge pull request #18 from futurice/master

Bugfix in GCM handler, multicastResult was always null