updated; driver to 1.3.18
ocd
overwrite option for update works now

So, we added overwrite support in 3.7 with the addition of mquery, but
it wasn't actually working... woops. This fixes that.
tests; remove .only
Added tests for nested and/or queries

These already worked, just needed to add tests for them.
Merge pull request #1634 from 10gen-interns/andor

Added tests for nested and/or queries