SERVER-14887 Remove user document validation from the storage layer.

User documents are validated in the user management commands, validating them in the storage layer
makes the system less flexible and causes problems with mixed-version replica sets.
SERVER-1424 (re)smoke tag parsing and new test library, v0

Includes:
- Smoke.py options for filtering by jstest tags
- New resmoke.py test utility in v0 alpha
- Lots of example resmoke configurations
- SCons integration for unittests
- Sample tagged jstests
SERVER-13621 Add JS tests for backwards box coordinates
Merge remote-tracking branch 'upstream/master'