Remove psutil dependency on Windows.
Remove psutil dependency on Windows.

We install from source on Windows as the main supported distribution mechanism. psutil is an optional dependency and is the only module we currently depend on that needs to build Windows native code, which pulls in a big toolchain (MSVS, mingw or similar).

olegnev/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,olegnev/dx-toolkit,johnwallace123/dx-toolkit,dnanexus/dx-toolkit,andyshinn/dx-toolkit,johnwallace123/dx-toolkit,olegnev/dx-toolkit,jhuttner/dx-toolkit,olegnev/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,olegnev/dx-toolkit,andyshinn/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,andyshinn/dx-toolkit,andyshinn/dx-toolkit,jhuttner/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,johnwallace123/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,olegnev/dx-toolkit,johnwallace123/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,andyshinn/dx-toolkit,jhuttner/dx-toolkit,olegnev/dx-toolkit,andyshinn/dx-toolkit,dnanexus/dx-toolkit,andyshinn/dx-toolkit,jhuttner/dx-toolkit