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

These are the templates that had to be
within the last commit.

Emails sent from the vet request commentaries
are contains in templates now in the templates folder.

Logic from vet_commentary_request has been moved
to the VetCommentaryForm form. Further moved some
code to improve DRY.

Method test_form_with_duplicate_*'s second part
 gave a false-positive result as the form_data
 contained neither a DOI nor a Arxiv ID. The
 tests came back positive but actually they were
 not.

Add invalid form test for RequestCommentaryForm.
Tests contain having no Arxiv ID or DOI or trying to
 give an already existing identifier.

Add first form tests using Factory to test RequestCommentaryForm.

Move few constants to a seperate file away from models.
This implies minor edits in other apps relying on
these few constants.

Merge branch 'development' of https://bitbucket.org/scipostdev/scipost_v1 into commentaries/wip-jorran

This function helps to create form data from models.
See example given.

Removes some 40 lines of boilerplate, since CreateView
handles the creation of a new ThesisLink.

This commit contains the first working view test
for the `request_commentaries` view.

A CreateView class based view should replace the current
request_thesislink function based view, since it saves
many lines of code and is less error prone and more easily readable.

Merge branch 'refactor-theses' of https://bitbucket.org/scipostdev/scipost_v1 into commentaries/wip-jorran

Move form validation and saving of instances
to the form class. From here you are able to instantly
save your validated form to the database. Further
reduces the size of the views.
Form may need error handling on not having
found a Contributor before saving the form instance.

You can now just call ContributorFactory() to get a freshly instantiated
Contributor to be used for testing purposes.

You can use these UserFactory to create a new user with an
associated Contributor. I could not get it to work the other way around.

Create fixtures for contributors, groups and permissions.

A blank domain throws an error in /theses/.
I've also installed factory_boy (pip install -r requirements.txt
to get it) and set up a ThesisLinkFactory and a unit tests that
tests whether ThesisLink validates for a blank domain field.

Not sure if this is exactly how you're supposed to validate
a model, but it's a start. First unit test of the project, whoohoo!

This is recommended. Also give names like
MASTER_THESIS = 'MA' to avoid magic strings and allow for easy
reference, e.g. thesis.type = ThesisLink.MASTER_THESIS. This sort
of thing helps in maintainability of the codebase, since if we want
to change the abbreviation to 'MASTER' for some reason, we have it
defined in one place, and not in 100 places in the code.

test_forms.py, test_models.py, test_views.py, as per
recommendation of the two scoops book.

Also slightly pep-improves the models and views.

Lost order argument in query for CommentarySearchForm
results in the last commit.

Reduce the amount of logic in the `commentaries` and
`browse` views methods in the `Commentaries` app. Further,
added a return method to the `CommentarySearchForm` to help thin
out code in the view.