Add `$DOHQ_ARTIFACTORY_PYTHON_CFG` environment variable

[Jorengarenar]

$DOHQ_ARTIFACTORY_PYTHON_CFG environment variable for overriding the default location of configuration file without a need to make changes in the code. It helps in multi-user workflow, when writing to $HOME is restricted or when the file needs to be stored in designated location.

As added bonus, it enables a semi-compilance with XDG Base Directory Specification for interested parties.

[allburov]

@Jorengarenar could you rebase the branch on the current master so we can merge it?

[Jorengarenar]

@Jorengarenar could you rebase the branch on the current master so we can merge it?

Sure