Fixed benchmarks to actually output valid json

before it was just the console.log version of the object, now actually
calling JSON.stringify and logging that
small tweak to name of a benchmark
Update MongoDB dependency to 1.3.17
Merge pull request #1629 from reezer/patch-1

Update MongoDB dependency to 1.3.17
Fixed issue with positional operator on ref'd docs

Positional operator was throwing an error when you tried to update a
referenced document on another doc. fixes #1572
simplify test for 1572, ocd
Limit applies to individual items on population

fixes #1490, the limit is now respected on an item by item basis when
populating an array of items.
refactor 1613 test
update History
Update release-items.md
tests; convert id to string
added; promise support to mapReduce

closes #1628
docs; promise.fulfill()
enhanced; model.populate() now returns a promise
enhanced; model.ensureIndexes now returns a promise
tests; replace deprecated method names
fixed; query#remove works as documented

We now support passing query conditions and callback:

  query.remove({ x: val }, callback)

TODO: add to 3.7 release notes
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.