[Tech Debt]: started the CLI work for PR#49

This pull requests includes the very basic work to start end-to-end testing the arithmetic CLI integration

https://github.com/jspm/jspm-cli/issues/49
Along the lines of my previous comment - it's all preference :)

if you prefer larger funcs that cool with me. My reasoning again was to create several smaller functions that could easily be tested and reasoned about in isolation if needed