Merge pull request #382 from ulises/master

Document the use of sets as predicates to (where...)
Deprecate streams/over and streams/under
Merge branch 'master' of github.com:aphyr/riemann
Improved docstrings for with and default.
Deprecate within and without
streams/rate: document expiry better
JSON-decoded events now have correct timestamps.

Millseconds are not seconds.
Use a set to filter services.