This commit contains the removal of html from 'the important' models
 or at least contains replacements for model methods such as `print_as...()`,
 etc. etc. Except for `header_as_li`, methods are not completely deleted yet.

> Fixed/Improved the nested comments and comments in reports. They were
 not shown before.

> Improved DRY principle in several templates/codes.

> Created Managers in the `submissions` app to filter i.e. "pool" submissions
 (so exclude potential author from judging on his own publication) for the
 pool view in the query; not in the template!

> More...

The select_related method reduces the database load
 by a factor of +/- 5 on the list view.

Write tests and refactor html.

The url is based off of the DOI. Because the DOI is always the same,
making more than one factory instance crashes the detail page.

UnpublishedVettedCommentaryFactory does not have this problem,
as it has an empty DOI field and a valid (random) arxiv identifier.

Also fix missing template error for modified thesis links.

The Comment model now has a option to
 append a file (pdf, png, jpg) to itself.

Start with making commentaries pages responsive.

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

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.

Migrations involve appending default values to model fields

Basic tests to check response contains commentaires.

Write test for bug from last commit.

New Commentary requests were not completed
 as the `requested_by` field was not properly
 saved.

Test if the `vet_commentary_requests` is responding with
 the right Commentary object.

Passwords generated by factoryboy were directly
 put into the table as a string, unhashed! However,
 if the testclient tried to login, it used all
 auth methods a normal user uses as well. This caused
 the test user to never be able to login with the
 generated password.

Add tests to VetCommentary view, however
 the fixtures for groups remain empty (no permissions)
 causing problems with the ContributorFactory. Need some
 fix first, to have the groups work properly with the
 factories.

Add test to check expected ValueError
on processing form before validation.

Add more VetCommentary tests for the
three different possible valid form actions.

Add valid test for accepted `VetCommentaryForm`.
Further added factory for unvetted Commentary.