Expose Raft as JAX-RS Resource and client

**Work-in-progress**

This PR aims at exposing Raft instances through HTTP, it should provide the following features:

* A JAX-RS 2 compliant Resource exposing all methods of a Raft instance as an HTTP endpoint. This part is completed
* A Jersey-2 based client for accessing replicas exposed as JAX-RS endpoints. Also implemented.
* A JAX-RS ResourceConfig or Application that can be embedded inside any compliant container this allowing easy integration of Raft instance inside any Jax-rs application. This part is in progress.

**Note**: This PR is based on #62 as I am using the new POJOs inside the barge-jax-rs module.