Add support for querying CRDTs with Yokozuna

[bkerley]

Existing:

client.search 'sets2', 'set:asdfasdfasd'
# returns:
{"max_score"=>0.712317943572998,
 "num_found"=>1,
 "docs"=>
  [{"score"=>"7.12317940000000038303e-01",
    "_yz_rb"=>"bryce",
    "_yz_rt"=>"sets",
    "_yz_rk"=>"asdf",
    "_yz_id"=>"1*sets*bryce*asdf*52"}]}

Desired:

idx = client.index 'sets2'
results = idx.search 'set:asdfasdfasd'
# results is an array-like collection
results.first #=> the actual set
results.docs.first #=> the docs entry

Looks figuring out that the results are a set type either involves probing an entry's content type (which breaks if a user lies and says something is a crdt when it isn't), or adding an API to read bucket type properties.

[bkerley]

Should probably also Care about matching classes between self and other.

[christophermancini]

Tests pass. Code looks clean. Looks like there is good test coverage.

[christophermancini]

👍 772165d

[bkerley]

@borshop merge