Listen on multiple addresses

[markhildreth]

Adhere to the "Server Behavior" section of RFC 5780 for the simple server. Specifically:

• Run the server such that it is bound to two addresses, and two ports. This should mean starting up four sockets. Error if any of the four sockets cannot be created.
  • Address A, Port A
  • Address A, Port B
  • Address B, Port A
  • Address B, Port B
• For each socket, handle binding requests such that the "OTHER-ADDRESS" attribute includes the opposite address/port (e.g., the socket for Address A, Port B should return address B, Port A).