Task/category import fixture

Bug fix: [yes]
Feature addition: [yes]
Backwards compatibility break: [no]
Unit test passes: [yes]
Behat scenarios passes: [yes]
Checkstyle issues: [no]*
ChangeLog updated: [yes]
Documentation PR: 
Fixes the following jira:


Removed category fixture, added a lot of tests, and resolved bug where no category was imported in case of errors.