This commit makes several changes.

In the controller:

- duplicates the logs produced by the jobs. Initially they were only
  stored into allgo.log, now they are also forwarded to the container
  output (using the 'tee' command) so that the controller can read
  them

- add a log_task that reads the logs from docker and feeds them into
  the redis db key "log:job:<ID>" (this is implemented with aiohttp
  in order to be fully asynchronous)

- store the job state in a new redis key "state:job:<ID>"

- send notification to the redis pubsub 'notify:aio' channel when
  the job state has changed or when new logs are available

In the allgo.aio frontend:

- implement the /aio/jobs/<ID>/events endpoints which streams all
  job events & logs to the client (using json formatted messages)

In django:

- refactor the JobDetail view and template to update the page
  dynamically for job updates (state/logs)
    - allgo.log is read only when the job is already terminated.
      Otherwise the page uses the /aio/jobs/<ID>/events channel
      to stream the logs
    - the state icon is patched on the page when the state changes,
      except for the DONE state which triggers a full page reload
      (because there are other parts to be updated)