update the sender/receiver application

Apart from cwnd limitation, there are a few other limitations
	1) rwnd
	2) burst_limit
	3) sock send buffer
	4) sock receive buffer

To make the experiment effects more obvious, all abovementioned limitations
have been eliminate.

However setting a too huge value of sk_sndbuf/sk_rcvbuf might introduce
additional issue - SCTP is not very stable. How to determinte the appropriate
sk_sndbuf/sk_rcvbuf is criticial.

As long as the buffer sizes are larger than the Bandwidth Dealy Product, they
won't be the bottle neck.

BDP(path 1) = 100Mbps * 0.2ms = 2.5KB
BDP(path 2) = 54Mbps * 2ms = 12.5KB

Well... BDP is much smaller than I expected.