centralize versions in top-level POM
isolated protobuf RPC stuff in own module

* barge-api contains base objects (model), currently generated through protobuf but would be better to have POJOs
* barge-core contains the base replica logic and Raft protocole implementation itself
* barge-proto-rpc implements specific replica instance based on Netty/Protobuf client/server
fix wiring of modules and make tests more explicit
further separation of concerns between core and rpc

* moved some interfaces and annotations to api
* make proto-rpc depends on api and not on core
* create NettyRaftService that knits everything together

Integration test still failing but for apparently different reasons than in master.
Merge branch 'master' into isolate_rpc

Conflicts:
	barge-core/src/test/java/org/robotninjas/barge/NettyServiceTest.java
removed barge-api project and moved proto files to barge-core
make integration test pass

* fix number of threads in event loop
* generalize counter cluster
increase timeout for leader election
increase timeout for leader election to 1 min
reverted crappy change...
Merge pull request #46 from foldlabs/isolate_rpc

Isolate betty based RPC from core