Merge of following commits from Trunk:
r32609: * GroupDAV preference for addressbook-home-set (requires to register hooks)
r32610: missing groupdav hooks
r32611: fixed missing "users" of principal url in calendar-user-address-set
r32615: as the pricipal of current user is influenced by GroupDAV prefs, we have to include them in the etag
r32619: loop over existing addressbooks, to make sure each ab is only once in addressbook-home-set, even when selected multiple times in the prefs because of symbolic ab like "primary group"
r32620: urlencode and decode account_lid in url to cope with group-names with space in it, which stall iPhone OS 4.2 devices
r32621: fixed bug: GroupDAV/CardDAV PUT request to /addressbook/ changes owner, also checking now required ACL for moving contacts between addressbooks
r32622: returning "403 Forbidden" if addressbook_bo->save() fails, happens when writing new entries in ABs without ADD rights
r32623: * iCal on iPhone detects URL now correct
reverted calendar-home-set to report only users calendar, as reporting multiple break propfind
r32624: we need a real redirect, not just a proxy
r32631: fixed working in GroupDAV prefs and translation
