Peer blacklisting functionality

[alexdovzhanyn]

Not sure what the best way to implement this would be, but there should be a failsafe in the connection logic that blacklists connections from a peer that is potentially trying to DOS, or is just an unreliable peer (e.g. a peer with a bad connection)

[fantypants]

I think we can almost close this as the PSS (Peer Shuffle System) should reorder the bad peers.

[alexdovzhanyn]

Nah this isn't exactly the same, a peer can be "valid" i.e. has a good connection and is alive, but there can be other reasons for needing to blacklist