Do not use Administrator account in tests

Fixes tests after http://review.couchbase.org/28698

Depends-On: http://review.couchbase.org/28747
Change-Id: I13b1a991519073411ee0d8fff3092331dcba6022
CCBC-263 Skip unfinished SASL commands

During rebalance, it is possible that the newly added server doesn't
have chance to finish SASL auth before the cluster will push config
update, in this case packet relocator messing cookies.

Change-Id: Ic3fb01b4a39d2e8e68c690c264a2918d631d9602