few fixes on UPR

to make UPR compatible with secondary index.

- Added VBuuid field in UprEvent which gets populated from UprStream.
- makeUprEvent() now accepts `stream` parameter to fill up UprEvent with
  relevant fields from UprStream.
- Added back UprStreamEnd.
- Fix corrent opcode for StreamReq.

Change-Id: I02563b34f03ed6aa710ba9d52b4f35fa16d9e227