Add cypher batch capability

[benitoDeLaCasita]

Add an execute_cypher_batch method in service that takes an array of cypher queries. A query can be a string or a hash for parameters ( exemple: {query: 'MATCH (n { property: {property} }) RETURN n', :params => { property: 3 }} ).

[therubymug]

Hello @benitoDeLaCasita, thanks for the PR. Do you mind looking into the failures on Travis CI? https://travis-ci.org/therubymug/keymaker/builds/29139357