Update qs to 1.2.0

qs had the following breaking changes:
- Square brackets get urlencoded (see: hapijs/qs#8)
- Use date.toISOString() for date serialization (see: hapijs/qs@e4731562502b8c4b5c1a505514dcfa083bedf12c)
Also update better-assert
Merge pull request #435 from wercker/feature/qsupdate

Update qs to 1.2.0