[EXT] Improved the indication of master node in the `__print_cluster_info` method of the testing cluster
Fixed the incorrect Git URL in the `rake setup` task
[EXT] Removed the dependency on the "backup" gem

The `bundle install` command was failing on Ruby 1.8.7 because of:

    Gem::InstallError: httparty requires Ruby version >= 1.9.3.
    An error occurred while installing httparty (0.12.0), and Bundler cannot
    continue.

Mocked out the Backup gem's modules and class in the unit test.
[EXT] Added more defensive code in the `Test::Cluster#__print_cluster_info` method

Constantly failing on Jenkins...

https://build-eu-1.elasticsearch.org/job/es-ruby_core/ES_V=1.3_nightly,RUBY_V=1.9.3-p448,TEST_TYPE=integration,jdk=JDK7,label=metal-pool/lastBuild/console
Release EXT:0.0.17
Added, that the folder with the extracted build is removed in the `elasticsearch:build` task
[EXT] Removed the deprecated options for launching the test cluster
[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'