Creating a new ThesisLink didn't save the `requested_by`
 field, causing trouble in for example the vet view
 for these specific objects.

Improve the templates using template tags.
 Further, wrapping the `content` block in the
 `container` div element.

Test if thesis is vetted/deleted and mail is sent in
the accepted/refused case.

Merge branch 'fix-thesis-vetting' of https://bitbucket.org/scipostdev/scipost_v1 into fix-thesis-vetting

Altered the message alert class and positioned it absolute to
 the body to have floating messages.

Add missing migrations

Migrations involve appending default values to model fields

Improvements submissions

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.

Theses that are accepted are vetted by the correct contributor.
Mails are not yet sent. Thesis is not yet deleted when refused.

Work in progress. All unvetted theses are now listed at
theses/unvetted_thesislinks. Vetting editors click on
a thesis link to vet, and are redirected to
theses/vet_thesislink/<id>, where they can change fields of a thesis
link.

theses/vet_thesislink/<id> is now a regular update view. It does not have
mail capacity, or refusal reasons, etc. I will work on that next.