Add post about running a working group

This post is a guide to running a successful working group.

Change-Id: Id31ab3943736c8f7029800dc3b8a9dddfe5953e6
Reviewed-on: https://gerrit.causes.com/30358
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Henric Trotzig <henric.trotzig@causes.com>
Add post about test performance

I started thinking about this a while ago when Shane and John sped up
asset compilation and wanted to right something about it. I think it's a
matter that is often neglected.

Change-Id: I932443b92f304aa64dcc0286120488b76830e864
Reviewed-on: https://gerrit.causes.com/30359
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Henric Trotzig <henric.trotzig@causes.com>