added tcp based repeater

[kelaneren]

#204

It's very useful for some cases.

[mrtazz]

Thanks for taking the time to submit this! As the functionality is very simple to the existing repeater, it would probably make sense to fold them into one and have a configuration option to use either UDP or TCP. Thoughts?

[kelaneren]

yes, it could. I kept it separately for a few reasons:

1. tcp connection is much more expensive than sending udp packet. So in the tcp repeater I used connection pool which is a unnecessary node module for udp one if you don't care about tcp.
2. keeping them separate, you could have both at the same time. after merging, you only can use either of them.

I am going to send you another pull request for the merged version. You decide which one you keep. Also, one connection pool bug is fixed in the new pull