public static void setAvatarUrl(@NonNull final IAvatar connector, final String avatarUrl) {
        putString(connector.getAvatarPreferenceKey(), avatarUrl);
    }
Set avatar URL by connector. Should SOLELY be used by class {@link AvatarUtils}!

@param connector the connector to retrieve the avatar information from
@param avatarUrl the avatar url information to store
main/src/main/java/cgeo/geocaching/settings/Settings.java