dashboard: database updater for performance dashboard This CL moves code from code.google.com/p/dvyukov-go-perf-dashboard, which was previously reviewed.
dashboard: database updater for performance dashboard
This CL moves code from code.google.com/p/dvyukov-go-perf-dashboard,
which was previously reviewed.

LGTM=adg
R=adg
CC=golang-codereviews
https://codereview.appspot.com/97250044

t-yuki/go.tools.old,t-yuki/go.tools.old,t-yuki/go.tools.old