Python packages - Makefile polishing

Some Makefiles, which are in our feed doesn't look good. This PR removes things, which are not necessary like PKG_UNPACK which are required when you are doing packages for both Python variants, but packages are now only for Python 3. While I was at it I changed to download the package from files.pythonhosted.org, added PKG_LICENSE and PKG_LICENSE_FILES and re-order and tweak some things in Makefile. By polishing the Makefiles, it will be better to someone, who wants to create a package. It can be used as an example.

Before we can send it to OpenWrt, we need to check the dependencies. I'm not sure if we have them all. The other thing is I don't like the approach - Hooks/Compile/Pre += prepare_pyzmq_setup which is in pyzmq.