Play! framework for neo4j database

Features :
* embedded database (Only, no REST API for now)
* create your graph with models that extends Neo4jModel.class instead of Model.class. Plugin create the graph and do mapping for you.
* create an node index by annotation with @Neo4jIndex
* for each of your model, plugin generate an unique id (key)
* you can declare an index by annotation 
* you have access to the neo4j console with /@neo4j/console
* There is a command line "play neo4j:help"
* you can import an YML file into database by cli : "play neo4j:import" (see format with this file https://github.com/sim51/logisima-play-neo4j/blob/master/samples-and-tests/logisima-play-neo4j-test/conf/data.yml) 

NB:
Model class have to extend Neo4jModel class

TODO:
* See Lazy
* See delete a relation and save
