Fixed coveralls submission
Fixed coveralls submission

Summary: The coveralls plugin was not running on Travis CI due to a bad config

Test Plan:
- [Coveralls coverage report](https://coveralls.io/builds/4582534)
- [Build](https://travis-ci.org/MediaMiser/protobuf-activemq-rpc/builds/99342133)

Reviewers: #data_services_operations, simon.baribeau

Reviewed By: #data_services_operations, simon.baribeau

Differential Revision: http://phabricator.mediamiser.internal/D3888

MediaMiser/protobuf-activemq-rpc,MediaMiser/protobuf-activemq-rpc