ISPN-263 Handle cluster partitions

https://issues.jboss.org/browse/ISPN-263

I added one more commit with some test fixes.
you're right dan!
and if this first cust is supposed to have a single default policy I agree that's what you should do, but also I was expecting to have the user pick the strategy among some kind of policy enum (or even a pluggable implementation).

Also there is the case in which the policy is not based on the number of nodes being a specific number, but by expecting a specific View (provided externally). In such case the decision should be based on the fact that the subgroup of nodes that you can talk to include the primary owner for a specific key.