Cleanup changelog after some hotfix releases.

The backporting of some hotfix features, weren't executed all that cleanly.
Therefore some manuel cherry-picking adjustments are needed.
MainDossierTest rework: Manually cherry pick of 4d1510fcea4ec270d26c6d4ab9923d294fee92ff.
Added reviewer role on admin groups.
This role ensures that admins can see the menu bar.
Merge pull request #273 from 4teamwork/lk_reviewer_on_admin

Added reviewer role on admin groups.
Merge pull request #313 from 4teamwork/pg_3.1.x_backport_cleanup

Pg 3.1.x backport cleanup
Dossierdetails: Fixed label for the `end` attribute.
Merge pull request #317 from 4teamwork/pg_dossierdetails_label_fix

Dossierdetails: Fixed label for the `end` attribute.
Changed format of examplecontent excel to xlsx.
Added repository.csv to xlsx script.
Merge pull request #318 from 4teamwork/lk_xlsx_converter

Added script to convert repository.csv to a xlsx file.
Setup: Made reference number conversion dependent to the reference formatter.

The actual implementation works only for numbers in the `grouped_by_three`
format. With this easy check it's possible to support both formats in the
repository setup...
Merge pull request #345 from 4teamwork/pg_path_from_reference_fix

Setup: Made reference number conversion dependent to the reference formatter.
Define development packages: Preparation for Release 2.8.1.
Merge pull request #347 from 4teamwork/pg_development_packages

Define development packages: Preparation for Release 2.8.1.
Fixed outdated profile versions for og.base:default and og.examplecontent:default.
Merge branch 'lg-fix-metadata-versions'

Conflicts:
	docs/HISTORY.txt
Added viewlet to colorize special pages as dev, test, ...
Merge pull request #373 from 4teamwork/jin-colorization-viewlet2

Added viewlet to colorize special pages as dev, test, ...
Updated css for colorization viewlet.
Fixed widget definition for some date fields in tasks edit form.

Affected fields:
 - `expectedStartOfWork`
 - `date_of_completion`