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.

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.

This does not work yet. I wrote some failing tests, but while
I was doing that, I came to the conclusion that I want to make
the route of the get request different from the route of the post
request.

This custom factory subclasses factory.Factory,
and overrides the build method, so that the model_class
gets called with a dict of fields, instead of with keyword
arguments. This is the way Django form classes require data to be
passed to __init__.

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.

The acknowledgement message is no longer hardcoded in
theses/views.py, but resides in the top-level strings module.

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

New Group defined: Developers.

New Permission: can_view_docs_scipost (necessary to view the /docs/).

Need to run the add_groups_and_permissions management command.

Haystack search facility was required and is installed, with Whoosh engine.

Requirements updated.

Instructions for setting things up:
haystack: http://django-haystack.readthedocs.io/en/v2.5.0/ (choice: Whoosh engine)
sphinx: http://www.sphinx-doc.org/en/1.5.1/
sphinxdoc: http://django-sphinxdoc.readthedocs.io/en/latest/

In particular, a Project has to be defined in app sphinxdoc in order for docs to be displayed (starting at /docs/).

New host_settings needed:
HAYSTACK_PATH (for the location of the Whoosh index (suggestion: project's root); make sure this is not readable by site visitors)

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.