cypher queries handle nil property values correctly
Merge pull request #80 from subvertallchris/master

cypher queries handle nil property values correctly
single ExecutionEngine instance in embedded DB
Merge pull request #83 from subvertallchris/master

single ExecutionEngine instance in embedded DB
Merge branch 'master' into query

Conflicts:
	lib/neo4j-core/query_builder.rb
	spec/neo4j-core/unit/query_builder_spec.rb