The celery-cmd script should have a parameter for celery-beat-db location

[jwkaltz]

Is your feature request related to a problem? Please describe.
The celery-cmd script currently writes the celery-beat-db file in the same directory, there is no option to specify a different location. This is problematic when running as non-root.

Describe the solution you'd like
The celery-cmd script does not have a parameter for defining the location of the celery-beat-db file

Describe alternatives you've considered
n/a

Additional context
I have tested a change in this script, a pull request follows soon for this issue.

[mattiagiupponi]

merged in master