Added on_session_available method on Neo4j::Session which can be used to delay calling a method until a session is available, needed in andreasronge/neo4j#388
sets @props instance vars to prevent duplicate queries
load_node sends valid response to CypherNode.new instead of ID only
Minor fix for #92

just a nicer way to convert to Hash with symbolized keys
Merge branch 'master' into rspec-3-upgrade

Conflicts:
	spec/neo4j-server/unit/cypher_session_unit_spec.rb