feat: Merge pull request pelias#28 from pelias/layers-query

Add layers query

feat: Merge pull request pelias#17 from pelias/elasticsearch2

BREAKING CHANGE: Elasticsearch 2.x is now required

remove references to deprecated property _cache

Merge pull request pelias#26 from pelias/update_readme

fix: Use standard README header

Merge pull request pelias#25 from pelias/semver

Setup semantic-release support