Merge pull request #77 from foldlabs/demo-ui

Basic HTML UI for monitoring Barge cluster
introduce REST-based Key-value store over Raft

basic PUT interface
implement GET on keys
returns 404 when key is not mapped
extracted builder pattern for Application

this should make it easier to inject custom resources, providers and binders into the context
in effect the RaftApplication acts as a container
completed basic barge store

* moved main application from barge-jax-rs to barge-store
* extracted Leaders class to encapsulate enquiring stabilization of the cluster
* moved script packagers (for demo purpose) to barge-store
fix double ListenableFuture issue when retrieving commit

when committing to raft instance, returned Future itself encapsulates a future. We need some flatMap here...
added skeletal jepsen test project
fork server in the background when starting, redirecting outputs to files

only way to stop server now is sending kill -TERM! Need to implement proper stop...
can stop store server instance using REST interface /control/stop
extract configuration reader to own object