Adding meteorite package 'router'

 * Meteorite added
 * router package added
 * Some refactoring
 * Navigation working with router

TODO: add security for logged out users.
Added filtering + a loader page
Fix links inside the app to use Meteor.Router
Fixing gettingstarted link + splitting doc in 3
Change tagline
Branding change: piJS to pijs.io everywhere
Marketing improvement on homepage
 * Wording of homepage marketing blocks
 * Added a "They love pijs.io" block
 * Add twitter/facebook button
Get analytics to work with Meteor.Router
 * Add a 'stats' filter
 * Moved initialization of analytics into analytics.js
 * Added a debug flag to analytics object to ... debug
Fix social widget + re-rendering bugs on home

 * Fix twitter embedded tweets and follow button
 * Removed facebook - it's buggy now