fix command line for msi files (python 2.7.14 and others)

when portapy is installed, create a key for what version it is, if it doesn't exist. if it does, use that version.

have a command, pvm, that allows you to change which version you are using locally, or be able to change it in package.json, and reinstall portapy, so it'll automagically be that version.

github thinks this is a python package, because its mostly python files, in lines of code. This is cause by pip.py.

solutions

• add python files to vendored
  • github uses linguist for tracking vendored files/dirs. hit that readme for the docs on it
• download file like pip.py during the install process, so they dont need to be tracked. this would additionally help, as you could always get the most up to date/correct pip version for they python you downloaded.

The first solution is a one liner, so if you cant be arsed, just do that and make an issue to download realtime later. otherwise, solution 2 will take some lift, and will add maintenance cost, if the external URLs ever change, thats more stuff we have to keep track of.

for example, when i do

const python = require('portapy').binary;
// python === '/some/path/to/python'

important to keep it not the root level object, in case later we want to add like

const python = require('portapy').exec;
const output = await python('print(\'hello from python!\')')
// output === "hello from python"

or version checking

const python = require('portapy').version;
// python === '2.7.13';

point is to keep options open