Tune up README. Use official GHfM syntax. Improve rendering.

* Remove stray spaces signaling continuation of paragraphs
* Use asterisks as bulleted list indicator
* Remove unnecessary paired octothorpes for headings
* Tuned up wording for clearer sentences
Merge pull request #9 from matthewmccullough/readme-tuneup

Tune up README. Use official GHfM syntax. Improve rendering.