MB-10788: return vbucket uuid and seq number to mutations

For the commands set/add/replace/append/prepend/set_with_meta
and delete_with_meta, return the vbucket uuid and sequence
number of the associated mutation.

Change-Id: I9c5a81a14c043e3551f767c829ca5af04ec1ff58
Reviewed-on: http://review.couchbase.org/44323
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Sriram Ganesan <sriram@couchbase.com>
Check for bucket and vbucket existence in EvpGetItemInfo

Change-Id: I26a4bf6be5955475e6cfd57b14727be953d8aa0b
Reviewed-on: http://review.couchbase.org/44636
Tested-by: Sriram Ganesan <sriram@couchbase.com>
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
MB-12540: Refactor the way we track snapshot start/end seqnos

For the 3.0 release I needed to add snapshot sequence number
quickly and in doing so implemented an approach that was not
very good and prone to errors. The correct approach is to track
sequence numbers on disk and also to track them for each checkpoint
in the checkpoint manager. This change moves us to the better
approach.

Change-Id: Ifbdd6c87b06767ff8c6504c1058ce11195fa2428
Fix

Change-Id: I1148a8eb2c64984832b4663f70038711ac727212