nextIndex when sending entries to replicas was off by one

as per fig.2 in raft paper, nextIndex for each follower is the value of next index in log to send.
Was previously set to be same as matchIndex which is last index known to have been sent to follower
also simplified running to be a boolean instead of an int
Merge pull request #75 from foldlabs/next-index-off-by-one

nextIndex when sending entries to replicas was off by one
extracted Application object for reuse into other Jersey containers
upgraded Jersey to latest version and deprecated JDK 6 support

* Jersey 2.8 requires Java 7
* replaced jdk6 with jdk8
added Jetty-based server

Use Jetty to expose events stream through webSocket endpoint
factorize basic HttpServer test for Jetty and Jdk
failed ws init event test
introduce module for injecting multiple listeners through guice

* cleanup log directories of launched servers after test to prevent server tests from impacting one another
properly stop server and application
remove invalid jdk8 travis target