Remove unused requires
Remove unused :refer exclusion
One more unused require
First native client actions works: indexing (create, put), get, index exists

Basic structure is already in place and it is now clear that we will be
able to provide an API that matches our REST API almost one to one.

There is currently a problem that will take some travis-ci.org CI env tweaks:

 * ES cluster name needs to be specified when connecting, so it has to be known
 * We assume it is set via ES_CLUSTER_NAME

References #17, #18.
README updates
Port more indexing tests, implement Create Index via native client
Don't run native API tests on travis

We need ES_CLUSTER_NAME to be exported in order for the native
client to successfully connect.
Native client improvements: several admin operations

References #20