Solution for auto loading Ruby classes wrapping nodes, #349

I've tried to make it fast by caching lookup of mappings.
Make sure the checked_label_set is only created once, closes #349
Merge pull request #350 from andreasronge/issue349

Solution for auto loading Ruby classes wrapping nodes, #349
Bumped neo4j-core version 3.0.0.alpha.14 to use new Neo4j::Session.query API.
Specs B Passin'
Merge branch 'master' into devise-neo4j

Conflicts:
	lib/neo4j/active_node/labels.rb