Bug/migration problem issue 236 devel

Fixed the migration problem in devel branch by enforcing the version of django-debug-toolbar to version 1.9.0. I ran the tests locally and they passed.

It has to do with issue #236 (closed)

The proper fix for master branch will be treated separately.

merged

mentioned in commit 921fc993

mentioned in commit 0843af56

mentioned in commit 6f0e3afa

mentioned in merge request !159 (merged)