added Makefile
restore cron server
install: moved the apt-get blocks
set the locale to C.UTF-8 using update-locale tool
shutdown the container gracefully
specify `daemon off` option using `-g` cli flag
added GITLAB_CI_HTTPS_HSTS_MAX_AGE configuration option
added GITLAB_CI_HTTPS_HSTS_ENABLED configuration option
readme: add section on `Configuring HSTS`
readme: document NGINX_X_FORWARDED_PROTO option
removed internal redis server
readme: added note about upcoming removal of internal mysql server
readme: added mysql migration instruction
launch a redis container if we can connect to the host docker

When the redis connection parameters are not specified, the image
will try to spin up a redis container if it is able to communicate with
the host docker.

This is only possible if the following two options are specified in the
docker run command:
  `-v /var/run/docker.sock:/run/docker.sock`
  `-v $(which docker):/bin/docker`

This is primarily added to get the quick start guide to work without
much of a hassel.
Merge branch 'redis-server'