big sweep through README.md

changed language to not use the familiar 'you'-form
standardized casing for some terms, like [JavaScript vs javascript]
removed hard-returns (use a soft editor word-wrap)
restructured some text blocks
added separation whitespace to break up headers & paragraphs
collapsed some indented code-blocks to fenced
added fenced block types (bash, js etc)
tuned some header depths
trimmed some whitespace
fixed some typos
added new typos?
Merge pull request #63 from basarat/feature/readme

Upgraded readme