Add apache config file example for shibboleth

cherry-pick 4f9204445bca2
Only `^/secure$` to trigger shibboleth authentication, refs #775

cherry-pick 78645b2e9fe
Improve rake task mconf:stats, refs #796

cherry-pick fc1e7664b6f4, adapted because the rake task is in another file.
`invites/invite_room` to return the user id instead of profile id

cherry-pick 0074f25243b737757a679e02437d6658ac839f50