Make sure Ruby benchmarks work.
Set up discourse to run against Ruby head.
Provide a name when setting up Redis container.
Add docker container that runs Discourse against Ruby trunk.

* Fork of Discourse stable will be fixed to this commit's date. Reason
  being that we are only interested in how Ruby trunk will perform.
  Running against Discourse master will give us too many variables to
  track.

* Using Docker images of redis:latest and postgres:latest. This will
  just use the latest stable version of both Redis and PostgreSQL.