validation messages translated
initial infos.el.yml translation
proper renaming of the translation files
contenttypes file added
contentypes finished
infos.el.yml finished
messages.yml added
more translations
final translation
newline added
Added optgroup for relations done by groupby in contentypes.yml
A whole bunch of minor CSS tweaks to the backend..

pinging @peterboorsma @anketwokings
generated CSS
Merge pull request #1921 from rarila/relations-groupby

groupby for relations
Merge pull request #1922 from GDmac/2.0

ResourceManager extensions url was still pointing to /app/extensions
proper renaming of messages.el.yml
Update ResourceManager test for new extension location
Merge pull request #1923 from GawainLynch/hotfix/phpunit-tests

Update ResourceManager test for new extension location
Merge pull request #1920 from stakisko/eltranslation

Thanks, and sorry again!
Manually merging in #1926