[ACTIVEMODEL] Allow passing `:index` option to `MyModel.import`

Allows to index the data into a different index:

    Article.import index: 'new_articles'
[SETUP] Fix deprecation warning for Mocha
[SETUP] Depend on Mocha 0.13, older versions throw exceptions about `mocha/setup`

Please make sure to delete your Gemfile.lock and run `bundle`.

The "shoulda" gem depends on "bourne", which only recently
[upgraded](https://github.com/thoughtbot/bourne/commits/v1.3.0)
to Mocha 0.13.1.
Added the support for the Count API

Added the `Search::Count` API and a DSL support for the Count API.

The semantics is similar to the search DSL and API, the `Tire.count`
method takes the index name(s), query, routing parameters, etc.

    Tire.count 'articles'
    # => 5

    Tire.count('articles') { term :tags, 'ruby' }
    # => 2

    c = Search::Count.new('articles')
    c.value
    # => 5
    c.json['_shards']['total']
    # => 5
    c.response.success?
    # => true

See <http://www.elasticsearch.org/guide/reference/api/count.html> for more information
and the integration tests for documentation.

Closes #521
[#420] Fixed incorrect parsing of `indices` option when the alias contains `routing` values

If a routing value is set, Elasticsearch returns a key called "index_routing",
which can overwrite the "indices" or "index" value if it comes later in the hash iteration,
since that key also matches the regex "/index|indices/".

Closes #420
[#420] Added unit tests for the `Alias` parsing bug fix

Added tests for karmi/tire@8fae686, replacing tests from mriley/tire@835c4cd.
[GEMS] Updated the MultiJson dependency to ~> 1.3

Closes #549
Release 0.5.4
[TEST] Removed the randomly and continuously failing test for `dis_max` query behaviour

Too many bogus errors like:

FAIL (1:00:22.911) test: Dis Max queries should boost matches in both fields.
                   <"Pinky Elephant"> expected but was
                   <"It's an Albino, Albino, Albino thing!">.
                   @ test/integration/dis_max_queries_test.rb:35:in `block (2 levels) in <class:DisMaxQueriesIntegrationTest>'
Updated Elasticsearch install instructions/code

Use the new service at http://download.elasticsearch.org.
Use proper capitalization: Elasticsearch