Exercise 2i sort parameter

The default when sort is off is undefined, but this test at least tries
to verify that results are sorted when it's set or defaults to true.
Notice that sort order is not key, but rather <2i term that matched>/key


/cc @russelldb This is the rebase/merged/reworked for 1.4 version of the test needed for the 1.4.4 release. Did you have to tweak other tests during the review? Anyway, I will be trying all other 2i riak_tests in the 1.4 branch to see what else might need an update/sync with 2.0

This needs an update to the HTTP client to pass: https://github.com/basho/riak-erlang-http-client/pull/29