Add DTL->TT migration for modified sysconfig settings.
Merge branch 'master' of git.otrs.com:otrs/otrs
Fixed an issue where dynamic field links were not correctly generated.
Replaced support@example.com with service@example.com.
Fixed problem with statistics caching in memory.
Added prio key to DynamicField config.

-To influence the order on which the objects to add dynamic fields to are displayed on the screen.
Renamed index personal_services_queue_id to personal_services_service_id
On system Maintenance fixed ValidID server error message, Change Comment field as mandatory including DB scripts.
Prevented call to GetSubscribedUserIDsByServiceID() without ServiceID.
Modified session handling usability on system maintenance.
Fixed system maintenance unittest.
Modified session widget name.
Merge remote-tracking branch 'upstream/master' into otrs-master