MB-8495 Increase docs_total estimate when docs_left increases.

It does not fix the root cause of the referenced bug. There we just
happened to see CHECKPOINT_START/CHECKPOINT_END messages. But since
it still seems to be possible to hit the same issue when there're
mutations going on during rebalance, I decided to make this fix.

Change-Id: Ic6b3ad28806ce1f353ca98882372b75e7930caf4
Reviewed-on: http://review.couchbase.org/28275
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-5904 - change ns_config format of rouser credentials

from {"user","password"} to {"user", {password, "password"}}
so existing sanitization works for this password too

otherwise I will have to write special handling
for messages like this one:

config change:
read_only_user_creds ->
{"ruser","asdfghytr"}

Change-Id: Ie8e7892fca077f7f54abbee027234b3b939136d3
[alk@tut.by: fixed no-auth case]
Signed-off-by: Aliaksey Kandratsenka <alk@tut.by>
Reviewed-on: http://review.couchbase.org/28270
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Merge remote-tracking branch 'origin/2.2.0'

* origin/2.2.0:
  MB-5904 - change ns_config format of rouser credentials
  MB-8495 Increase docs_total estimate when docs_left increases.

trivial merge

Change-Id: Ic70733fb9df266ca4e6c05761c2793ea046c9702