[#916] Added support for the Suggest API (@marc-villanueva)

See: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-suggesters.html

Related: #916, #894, #857, #777
[#857] Added support for the Suggest API (@fbatista)

Still needs more tests and support for other more types other than completion

See: http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-suggesters.html

Related: #916, #894, #857, #777
Added suggest support to the model integration

Related: #916, #857
Suggestions: Exception raised outside `Search` module, use fully-qualified name.
Suggestions: Shortcut method in DSL
Suggestions: Fixes for completion multi
Suggestions: Integrated @marc-villanueva stuff with @fbatista PR

Related: #777 and #857
Suggestions: Fixed failing unit tests
Suggestions: Working integration test within search
Suggestions: Integration test for standalone completion
Suggestions: Integration test for standalone suggestions
Suggestions: Allow options for completion
Fixed failing test on 0.90.7
Suggestions: Added information about the topic into `tire-dsl.rb` documentation
Suggestions: Small edits to the relevant chapter in `tire-dsl.rb` documentation

Closes #916
Closes #894
Closes #857
Closes #777
Release 0.6.2
Added, that Index#retrieve throws an exception on HTTP errors

Closes #929
Added unit test for the error handling in Index#retrieve

Related: #929
Fixed `Index.retrieve` so that it works with ES 1.0.0 and previous versions

Closes #939
Added notice about 1.0 compatibility to README, added link to elasticsearch/elasticsearch-rails

Related: #943