Code drawn rockets

• Removed jQuery dependency by converting backdrop code to pure JS
• Rockets are now code drawn using the colours specified for the rocket
• Removed rocketIcon and rocketIconSize properties
• Removed Font Awesome inclusion now that rockets are code drawn
• Backdrop colour is darker and and does not animate
• Fixed small issue with light horizontal line near bottom of buildings
• Rocket trails contain less particles and fade from the bottom up over time