Provide a more readable representation of socket on repr().

Before:
<socket.socket fd=3, family=2, type=1, proto=0, laddr=('0.0.0.0', 0)>

Now:
<socket.socket fd=3, family=AddressFamily.AF_INET, type=SocketType.SOCK_STREAM, proto=0, laddr=('0.0.0.0', 0)>