Don't hard code reference formatter in tabbed view custom sorter.
Preparing release 3.2.3
Back to development: 3.2.4
Merge pull request #219 from 4teamwork/lg-reference-number-sorting

Don't hard code reference formatter in tabbed view custom sorter.
Updated move destination widget to hide closed dossiers.
Fixed typo at workflow name in mock test.
PEP8.
Replaced hardcoded workflow names with constants.