extracted class for dedicated http server
created main barge HTTP server that takes some cluster configuration and logs what happens

this is mostly for demo purpose to see what' happening inside a raft instance when it is running
guard against null message when checking terms

don't know why message would be null though...
added helper script for running raft http server cluster

* barge.conf is a sample configuration file describing a cluster
* init.sh sends init signal to all instances in barge.conf
* send.sh sends some data to a single running instance for committing
* running java -cp brage-jax-rs.jar pack generates a self running barge.sh script in current directory