ISPN-263 Handle cluster partitions

https://issues.jboss.org/browse/ISPN-263
A good starting point is the documentation commit which describes the implemented functionality.
Most of the code is around playing with state transfer so dan's input is important :-)
I've added:Enabling partition handling is critical for applications that have high consistency
requirements: when the data read from the system must be accurate (e.g. when holding
bank account information). On the other hand, if Infinispan is used as an best-effort
cache, e.g. to cache web pages in a proxy, the partitions are perfectly tolerable.