hydra-evaluator improvements

* The "Jobset" page now shows when evaluations are in progress (rather
  than just pending).

* Restored the ability to do a single evaluation from the command line
  by doing "hydra-evaluator <project> <jobset>".

* Fix some consistency issues between jobset status in PostgreSQL and
  in hydra-evaluator. In particular, "lastCheckedTime" was never
  updated internally.

src/sql/upgrade-53.sql

@@ -0,0 +1 @@
+alter table Jobsets add column startTime integer;