Fixed incorrect syntax usage and missing environment variables in cron jobs

Previously the Cron config file at docker/config/aurweb-cron was using incorrect syntax, leading to jobs not running. The jobs previously didn't have the root declaration before the bash command (which is where the user is supposed to be specified), which causes cron to try to run the job as the bash user (which doesn't exist, thus causing the issue) instead of root.

The AUR_CONFIG environment variable also isn't exposed to the cron jobs (presumably due to cron not taking the user's environment when starting up), thus causing the jobs to fail even after the aforementioned issue is fixed. This was fixed by adding the AUR_CONFIG variable into the Cron config directly.

Lastly, the -x proc flags were added to the startup command for crond. The AUR_CONFIG issue wouldn't have been revealed without it, and I think their presence would help if any issues in the future were to arise. I can remove this if it would be preferred without it though.

Closes #206 (closed) and #207 (closed).