Cluster: fix logic to detect we are among a minority.

In the cluster evaluation function we are supposed to set the cluster
state as "fail" if we are among a minority, however the code was not
detecting to be into a minority partition if exactly half the masters
were reachable, which is a minority.
Cluster: process gossip section only for known nodes.

With the exception of nodes sending MEET packets: we have to trust them
since they can send us MEET packets only when the cluster is initially
created or because sysadmin manual action.
Fix DEBUG POPULATE warning for lack of casting.
02_upload_tarball.sh: let me exit before updating site.
Merge branch 'unstable' of github.com:/antirez/redis into unstable