Merge pull request #39 from townxelliot/touchscreen-nav_xwalk-863

Enable detection of touch events which trigger navigation
Rejig content of Getting Started
Updates to the Documentation section

This is a rewrite of the Documentation section of the website
from scratch.
Finish Linux install instructions
Flesh out and verify dev tools installation instructions
Complete host/target install instructions
Use standard markdown syntax for code blocks
Add instructions for setting up Android targets
More instructions for Android/Tizen targets
Complete first draft of docs rewrite