Share & Remix panel updates.

This is the little panel that slides up with the orange tab.

Changes:
* Added QR code for sharing
* Added Email Remix link feature
* Added Email to Share feature
* Removed 'Install App' button when app is already installed
* Remix button opens a Email Remix popup when not on desktop

Tested on:
* Desktop Chrome
* Desktop FF
* Firefox OS
* Firefox on Android

no need for `false` in addEventListener, the browser will default to this unless you use `true` (it's an obscure event handling flag)