Fix xcontent serialization of timestamp/routing index field

The index field was serialized as a boolean instead of showing the
'analyed', 'not_analzyed', 'no' options. Fixed by calling
indexTokenizeOptionToString() in the builder.

Closes #3174
Using AtomicArray to collect responses in mget and bulk indexing (instead of synchronised)
Add info to _cat/nodes, add _cat/indices.
AtomicArray.toArray will now throw an exception if target array if of the wrong size.
Added statistical facet to term facet in SimpleNestedTests

The test now uses a statistical facet plus a filter facet on nested documents.
rename variable and add comment about TopDocs#merge
Removed useless TODO
Fixed nullshape indexing.
Closes #3310
Added support for multiple indices in open/close index apis

Open/Close index api supports now multiple indices the same way as the delete index api works. The only exception is when dealing with all indices: it's required to explicitly use _all or a pattern that identifies all the indices, not just an empty array of indices. Supports the ignore_missing param too.
Added also a new flag action.disable_close_all_indices (default false) to disable closing all indices

Closes #3217