Include licenses for the code I've borrowed.

[Lukasa]

I've borrowed a pair of chunks of code (SocketServerThread in the tests and DeflateDecoder in the response) from @shazow's urllib3 project. Technically the MIT license requires that I distribute it along with that code, which I should really do. =)

[Lukasa]

I also think @alekstorm has grabbed some code from the Python standard library and from CherryPy: I should add those licenses as well.

[shazow]

IMO just shove them all in a single file. The license file headers thing is kinda BS anyways (I've been meaning to strip them from urllib3).

[Lukasa]

Yeah, I think I'll add a NOTICES file and then reference it from the relevant functions.