MB-21190: cbepctl support to change max_cas

MB-21190: cbepctl support to change max_cas

The initial version of this commit blocks *all* set commands
as it required they all pass a vbucket-id even when not
required.

This update means that changing max_cas is done via

 cbepctl set_vbucket_param

That command requires the vbucket-id.

This commit changes (reverts) to not requiring the extra CLI argument.

 cbepctl set

Change-Id: I04b8b607ccfbc56bca46fe55ca0360f0fe7874ef
Reviewed-on: http://review.couchbase.org/68736
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: buildbot <build@couchbase.com>