Add plural handling to e.g. 5 minutes

[rakekniven]

tasks/js/app/app.js

Line 167 in f6c11bc

mm: t('tasks', "%d minutes"),

See discussion at https://www.transifex.com/nextcloud/nextcloud/translate/#af/$/99690076?issue=yes

[raimund-schluessler]

Fixed with #194.