AddressTranslator implementation for a multi-region EC2 deployment where clients are also deployed in EC2.

Its distinctive feature is that it translates addresses according to the location of the Cassandra host:

addresses in different EC2 regions (than the client) are unchanged; addresses in the same EC2 region are translated to private IPs. This optimizes network costs, because Amazon charges more for communication over public IPs.

The default AddressTranslator used by the driver that do no translation.