SERVER-10026 temporary js tests with explain removed (round 2)

This pull request is for Hari, to help him test SERVER-10026. See me or Dan with any questions.

Adds jstests/queryTmp directory. This time around I've replaced calls to cursor.explain() with cursor.itcount(), and generally asserted that the count is correct. All of the tests in the "explainfails" file that Dan sent me now have updated forms in jstests/queryTmp which will not fail due to explain().

See the tests triage doc for tests that are BROKEN (i.e. don't work even after replacing explain() calls) and tests that are FIXED (already work in the new query codepath without modification).