parse index structure from response

add the indices to meta.index on get as they are defined when
setting them via ```meta.index = { foo: 1, bar: "baz" }``` on save.

FIXES #183
repositories is not (no longer) valid

it should be repository, since the array only contains one element
anyway it can just be removed I would say. This stops npm from
complaining about it.
Merge branch 'fix-repositories-to-repository' into riak-2.0
Merge branch 'reading-2ii-to-meta' into riak-2.0