Feature/mongo 2.6.5 matcher matcher

Edits to:
 - /lib/pipeline/matcher/Matcher2.js
 - /test/lib/pipeline/matcher/Matcher2.js:
   - Importing the mongo tests that we support in mungedb-aggregate (not including Within tests, Where test, or timing test).

I merged this with MatchExpression, so that's what the other file diffs are.
Probably should try to figure out if we can craft a test that hits this line too - looks like passing a json string instead an object will make it happen.