Make sure django is loaded if it is not already loaded

[javierggt]

Description

This PR would Fix #201.

The way it is currently set up, kadi loads django if the DJANGO_SETTINGS_MODULE is not defined. The assumption is that, because django sets this variable during loading, if it is defined it means django is loaded. This fails when a child process is spawned, because the variable will be defined for children processes, but the children processes do no inherit the python module.

I added another condition for loading django. Namely, that the manvrs variable is not defined within kadi.events.

Possible things to do:

• remove the check for DJANGO_SETTINGS_MODULE
• does this check need to be made elsewhere?
• add a unit test case with the gist from #201 (or some other test involving spawned processes).

Testing

• [x] Passes unit tests on MacOS. (well, it actually fails, but already failed before this change)
• [x] Functional testing. Used the gist linked to in issue #201

Fixes #

[jeanconn]

I think this PR has been lingering and might be useful. @taldcroft did you have thoughts for more testing? Largely I'm just wondering which open or merged PRs should really just get in to a ska3-matlab without much fuss.