1.add use of ThruputMeter and ThruputMeteringChannel to collect thruput
infomation of both client and server on uplink and downlink.
2.use 3 types of channels to simulate different datarate and delay of
client uplink and downlink as well as the server link
change 
**.batchSize = 500
**.maxInterval = 0.001s
from nsc_general to script to fit both simpleWebPPP and simpleWebThruput
network configure.