Unix philosophy of clarity

Hey Sandy,

I've added a new guideline which I've taken from the unix philosophy handbook. The guidelines talks about about clarity being better than cleverness, https://github.com/flashmedia/node-style-guide/tree/furtheredits#clarity-is-better-than-cleverness.

What do you think?

(I've also removed the 80 characters per line guideline, and updated the ternary operator guideline).