Add blocking function to block osd thread when CoDel condition is violated

[yzhan298]

When we set the kvQ capacity to 1, we allow 1 reqs to get into the kvQ. For these two lines:

env.process(osdClient(env, 1, meanInterArrivalTime * 2, meanReqSize, osdQ1))
env.process(osdClient(env, 2, meanInterArrivalTime * 2, meanReqSize, osdQ1))

Does it mean that we should get the ten in order 2,1,2,1,2,1.,..?
But I noticed that we could have order 2,1,2,1,1,2,.... Does this mean we have a priority inversion?
If so, we could count the number of inversion.

The result is shown in the CoDelTest/simulation-codel-out.ipynb. I can compare the inversion number, average throughput, and average latency between blocking and non-blocking case.