Merge pull request #1312 from nextcloud/enhancement/vue-external-avatars

lib/Contracts/IUserPreferences.php

lib/Controller/PreferencesController.php

lib/Service/UserPreferenceSevice.php

package-lock.json

src/components/AppSettingsMenu.vue

src/components/Avatar.vue

src/components/Envelope.vue

src/main.js

src/service/AvatarService.js

src/service/PreferenceService.js

src/store.js

src/tests/unit/util/undefined.spec.js

src/util/undefined.js

tests/Controller/PreferencesControllerTest.php