Fix Docker file ownership issues:

[arikfr]

1. Simplify user creation to create a non system user (so the uid will usually
   match the host user).
2. Set the user to redash & remove the need to change user in docker entrypoint.

[44px]

@arikfr, can these changes broke redash_worker container?

After pulling latest changes I noticed that queries stuck in queue.

docker-compose ps shows this:

redash_worker_1     /app/bin/docker-entrypoint ...   Exit 1

redash_worker_1 shuts down soon after start (I checked multiple times)

docker logs redash_worker_1 ends with:

worker: Warm shutdown (MainProcess)
[2017-03-16 21:04:13,956: INFO/MainProcess] beat: Shutting down...
Starting scheduler and 2 workers for queues: queries,scheduled_queries,celery...
Running a worker with superuser privileges when the
worker accepts messages serialized with pickle is a very bad idea!

If you really want to continue then you have to set the C_FORCE_ROOT
environment variable (but please think about this before you do).

User information: uid=0 euid=0 gid=0 egid=0

I restored sudo -E -u redash in bin/docker-entrypoint and queries queue works as before now.

[arikfr]

You need to rebuild the container (docker-compose rm server / docker-compose rm worker and then create or up).

[44px]

Thanks, it works!
A bit strange - I tried docker-compose rm and then docker-compose up previously, but it didn't help.