CAUTION! READ ME!
This migration will setup a proper attachment environment.
This means, that for existing files (journal publication!),
 these folders/files should be completely moved to the MEDIA_ROOT
 folder, else this will return a 404 NotFound for the related
 files.

Improve comments app to follow PEP rules
 and remove all wildcard imports!!

Improve HTML structure for journals
 such that all elements are aligned with
 eachother and most content is repsonsive.
 Biggest thing to do still is the journal-menu
 which is not reposnive yet.

In the journals app, the Issue model is extended
 with a status field. This is published by default,
 but has a draft options such that a journal can be
 created without being shown. Incomplete issues
 can cause errors for visitors, so use the draft status
 if an issue is not "visitor-ready" yet.

Change all involved tests. Start moving email to templates.

Update all involved tests. Also extend model_form_data to
accept an argument `form_kwargs` to pass to form.

Start with making commentaries pages responsive.

Start transforming the prefill with Arxiv commentary request
 to a class based view using the Arxiv caller.

Alter ArxivCaller to inheriting from BaseCaller
 and slightly alter the caller workflow. This
 prepares to be able to use ArxivCaller in
 for example Commentaries as well. Further
 initiate empty DOICaller which should
 be used to do similar work but with a DOI.

Prepare ArxivCaller to be used in multiple models.
 It includes the creation of a ArxivCallerMixin in the
 behavior file which should be used in all objects using
 the ArxivCaller.

Move ArxivCaller to the scipost folder, since this caller
 will be used by more apps, such as the commentaries
 apps.

RequestCommentary is transformed to a class based view. Further
 moved strings to `/strings` and used django.messages middleware
 to pass messages to the user instead of context data.