MB-8545: do not allow node self-rename when name is set manually

Change-Id: I7f7721fe6fc7b0fd6b60d60984a4f28089bbfcb1
Reviewed-on: http://review.couchbase.org/27264
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
MB-7398: reset user-assigned hostname when leaving cluster

I.e. otherwise we have no way of "undoing manually assigned hostname".

Change-Id: I2ca3c78804413619b974f3031e675ee6f9cc8526
Reviewed-on: http://review.couchbase.org/27265
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
MB-100: updated CHANGES

Change-Id: I33eed74bc221c31807376535eaa88874528c1efa
Reviewed-on: http://review.couchbase.org/27266
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>