remove unused lines that break python 3.x

I have yet to get tests to fully work (trouble importing async.mod.zlib), but these changes remove imports that are not used in the code and break python 3.x.  The module new and the threading _Condition go away in python 3.

I know that you say you are not planning on going to python3, but these changes do not hurt python 2.7 and help towards python3.