Mesos 0.17.0 support.

The issues with supporting Mesos 0.17.0 are related to incompatible old dependencies. The resolution consisted in:

- Bumping the Mesos version from ```0.14.0-RC4``` to ```0.17.0```.
- Bumping the Google Protobuf version from ```2.4.1``` to ```2.5.1```.

Alternatively, the ```/target``` folder should probably be added to ```.gitignore```. Please confirm that this is a safe operation and I will take care of it.