[EXT] Added removing the data folder for `cluster_name` to make sure the testing cluster starts green

Since the "store=memory" and "gateway=none" options have been removed, the data were left between
cluster restarts, and the default index settings with 1 replica prevented the "green" health,
timeouting the cluster launch.

Related: e6f8111
[EXT] Make sure the `cluster_name` argument is not empty/dangerous in test cluster launcher

Related: ef05b21
[API] Renamed the `termvector` API to `termvectors`

Related: elasticsearch/elasticsearch@1959275622ca35997420213d979a1724944aa4f6
[DSL] Initial commit to "elasticsearch-dsl" Rubygem
[DSL] Updated .gemspec and added Rake tasks
[DSL] Added the test helper
[DSL] Added the main DSL module
[DSL] Added the `BaseComponent` module for the DSL
[DSL] Added the initial Query implementation

* `Search` class with a `query` method
* Query classes for initial queries (match, range, term)
* Unit tests for all classes
* Basic integration test for the `match` query (skeleton for others)
[DSL] Added documentation for the current codebase
[DSL] Added the initial Filter implementation
[DSL] Added the `call` method to the BaseComponent
[DSL] Added BaseAggregationComponent with common logic for aggregation classes
[DSL] Added the Aggregation class to wrap aggregations in search definitions
[DSL] Added the "Terms" and "Range" aggregations
[DSL] Added the aggregations integration into the DSL

    response = client.search index: 'test', body: search {
      aggregation :tags do
        terms field: 'tags'
      end
    }.to_hash

    response['aggregations']['tags']['buckets'][0]['key']
    # => 'one'
[DSL] Added a sorting integration
[DSL] Added the support for search definition options (from/size, version, explain, ...)
[DSL] Added the support for search suggestions

    search do
      suggest :title, text: 'th', completion: { field: 'title_suggest' }
    end

See: http://www.elasticsearch.org/blog/you-complete-me/