Consider a robust TCP / etc communication fabric

[frankmcsherry]

Right now the "most distributed" communication fabric is a TCP-based fabric that doesn't think too hard about complicated things like data corruption or disconnects. The communication crate is meant to be designed in a way that allows folks to drop in their own communicator implementation, but it seems like one that could be generally useful is one that hardens the TCP based framework with things like CRCs, buffering and retransmission, reconnection if disconnection occurs; stuff like that.