mcserver: log if vbucket master is heuristically changed
mcserver: log if vbucket master is heuristically changed

Change-Id: Ic700abeccfe1ad0b68898c54bc7f524ea68caa36
Reviewed-on: http://review.couchbase.org/42402
Tested-by: Mark Nunberg <e7d42768707bf23038325b0b68d4b577e5f6064a@haskalah.org>
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>

couchbase/libcouchbase,couchbase/libcouchbase,avsej/libcouchbase,mody/libcouchbase,senthilkumaranb/libcouchbase,couchbase/libcouchbase,mnunberg/libcouchbase,avsej/libcouchbase,avsej/libcouchbase,mnunberg/libcouchbase,mnunberg/libcouchbase,kojiromike/libcouchbase,avsej/libcouchbase,signmotion/libcouchbase,couchbase/libcouchbase,mody/libcouchbase,signmotion/libcouchbase,senthilkumaranb/libcouchbase,kojiromike/libcouchbase,mnunberg/libcouchbase,avsej/libcouchbase,maxim-ky/libcouchbase,senthilkumaranb/libcouchbase,PureSwift/libcouchbase,couchbase/libcouchbase,PureSwift/libcouchbase,mody/libcouchbase,PureSwift/libcouchbase,kojiromike/libcouchbase,signmotion/libcouchbase,maxim-ky/libcouchbase,kojiromike/libcouchbase,mody/libcouchbase,couchbase/libcouchbase,maxim-ky/libcouchbase,senthilkumaranb/libcouchbase,maxim-ky/libcouchbase,couchbase/libcouchbase,PureSwift/libcouchbase,avsej/libcouchbase,signmotion/libcouchbase,mnunberg/libcouchbase,avsej/libcouchbase