Use locally running Elasticsearch instance

Doesn't spawn own instance of test cluster
Create Elasticsearch indexes before running specs

Also, for Travis:

* Run on Ruby 2.1 with allowed failure
* Don't run on 1.9.2 any more as we are on 1.9.3
Merge pull request #139 from alphagov/59667324-add-elasticsearch-to-path

Use locally running Elasticsearch instance