MB-6922: send 302 when handling no active vbuckets on view query
MB-6922: send 302 when handling no active vbuckets on view query

So that clients can clearly distinguish hitting node being
rebalanced-in or -out and hitting dead ddoc or bucket. Also Location
header will point client to better node which is helpful as well.

Change-Id: I5ed1066ba646a67d0197b67f3988251822dfec31
Reviewed-on: http://review.couchbase.org/21657
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

membase/ns_server,daverigby/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,vzasade/ns_server,vzasade/ns_server,nimishzynga/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,mschoch/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,nimishzynga/ns_server,pavel-blagodov/ns_server,daverigby/ns_server,daverigby/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,vzasade/ns_server,mschoch/ns_server,pavel-blagodov/ns_server,pavel-blagodov/ns_server,mschoch/ns_server,membase/ns_server,membase/ns_server,ceejatec/ns_server,mschoch/ns_server,daverigby/ns_server,nimishzynga/ns_server,membase/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,vzasade/ns_server,membase/ns_server,pavel-blagodov/ns_server