Implement Open Index and Close Index operations

References #20
Merge branch 'master' of github.com:clojurewerkz/elastisch
Native client: Support Optimize Indices and Flush Indices requests

References #20
Extract function
clj-http 0.6.4
Cheshire 5.0.2
Change log updates
Introduce native client in the change log
Native client: support Clear Cache operation

References #20
Native client: support Status requests

References #20
:native test selector
Native client: support Segments requests

Full response conversion is still to be done.

References #20
native client: support Update Aliases requests
native client: support Template requests

References #20
native client: support Refresh requests

References #20
Refer to fewer functions
Cosmetics
wording
link to clojurewerkz.org
Switch to ElasticSearch master snapshot because of massive API breakages in the client