Refresh-only VTS

With VTSManager, it is now possible to create refresh-only VTS-TSRs. Features of this type of VTS, fall between pure read-only and read/write VTS-TSRs.

If the tables in VTS are updated frequently, and a SWITCH process for every update is not feasible, refresh only VTS will be the right choice. The only update command allowed on this VTS is REFRESH.