Create a "getting started" guide

[cantrell]

Write a getting started guide for the site, and link to it from the README. It should include:

• Getting the repo (or downloading the zip file).
• Building it with grunt.
• Including the library.
• Initializing Snap.
• Drawing a couple of shapes.
• Animating them.

Write it up, and send it to Yohei for inclusion on the site.

[mike-sierra]

FWIW, my superficial review of the ref doc gave me the impression Snap works on three distinct problems: (1) extending jQuery-like convenience features to SVG; (2) extending familiar DOM API features to SVG, e.g., querySelector(), data-attr & drag/drop; (3) smoothing over differences in how some SVG features work compared to CSS, e.g., transforms. Maybe not appropriate for a basic "getting started," but it would be good to communicate points like these at a high level.