Supporting referencing objects in queries to query based on relationships.
Added some unit specs for Label.queries

Started to write pending tests for :where queries which works in a similar way to :match
Also, tried to make the 'n' variable in the cypher less magical.

Rebased latest from git@github.com:cheerfulstoic/neo4j-core
This commit is needed in andreasronge/neo4j#352
Merge pull request #71 from andreasronge/matches

Neo4j::Label.query with matches