fixup message.show template
i18n
fixup "add installation option adhocracy.instance.allow_logo_as_background"
more specific link text on event carousel
update CHANGES.txt
Merge branch 'develop' into geo

Conflicts:
	src/adhocracy/i18n/adhocracy.pot
	src/adhocracy/i18n/de/LC_MESSAGES/adhocracy.mo
	src/adhocracy/i18n/de/LC_MESSAGES/adhocracy.po