Fix High CPU occupancy

[kimw]

The dead loop causes high CPU occupancy. Quit loop when no more byte to copy.

[kimw]

fix #12

[kimw]

@cbeuw
I don't know go lang in fact. Just learned in about 30mins to debug #12. If I didn't fix the bug in golang way, I'm sorry.

BTW, should the (pair *webPair) serverToRemote() do the same change?

As from,

func (pair *webPair) serverToRemote() {
	_, err := io.Copy(pair.remote, pair.webServer)
	if err != nil {
		pair.closePipe()
	}
}

To,

func (pair *webPair) serverToRemote() {
	for {
		length, err := io.Copy(pair.remote, pair.webServer)
		if err != nil || length == 0 {
			pair.closePipe()
		}
	}
}

[cbeuw]

Yes serverToRemote needs to do the same.

I thought io.Copy would block when there's nothing to read. I tested the bypass feature before and I had probably completely overlooked the CPU issue. I hope people who are using gq-server on their VPS didn't turn on automatic CPU scaling, or that would be a lot of money wasted.

I didn't know either how I missed the for loop in serverToRemote.

Thank you very much for your contribution