* Added a status page that shows all the currently executing build steps.

* Store the system type in the BuildSteps table.
* Don't query the queue size when serving static pages.  This prevents
  two unnecessary database queries per request.

src/sql/hydra.sql

@@ -236,6 +236,7 @@ create table BuildSteps (
     stopTime      integer,
 
     machine       text not null default '',
+    system        text,
 
     primary key   (build, stepnr),
     foreign key   (build) references Builds(id) on delete cascade