Add Pipe support for Search mapred
Add Pipe support for Search mapred

az583

Since Pipe is Riak's new mapred engine Search needs to know how to
talk to it.

xuejianhai/riak_search,wwezhuimeng/riak_search,basho/riak_search,basho/riak_search,xuejianhai/riak_search,wwezhuimeng/riak_search