Fix mode to return string rather than int.

mentioned in commit fengweijie/gitlab-ce@6ab8275c

mentioned in commit fengweijie/gitlab-ce@2a0d38c0

mentioned in commit mrts/gitlab-ce@6ab8275c

mentioned in commit mrts/gitlab-ce@2a0d38c0

mentioned in commit sharcnet-web-team/gitlab-ce@6ab8275c

mentioned in commit sharcnet-web-team/gitlab-ce@2a0d38c0

mentioned in commit dmitrych61/gitlab-ce@6ab8275c

mentioned in commit dmitrych61/gitlab-ce@2a0d38c0

mentioned in commit bugagazavr/gitlab-ce@6ab8275c

mentioned in commit bugagazavr/gitlab-ce@2a0d38c0

mentioned in commit rickettm/gitlab-ce@6ab8275c

mentioned in commit rickettm/gitlab-ce@2a0d38c0

mentioned in commit klowner/gitlab-ce@6ab8275c

mentioned in commit klowner/gitlab-ce@2a0d38c0

mentioned in commit jeroenj/gitlab-ce@6ab8275c

mentioned in commit jeroenj/gitlab-ce@2a0d38c0