more controller support

[ngokevin]

I don't have a GearVR, but testing on Vive:

• Update to A-Frame master with some regressions cherry-picked out
• Controller models
• Camera scaler (use grips to zoom in / out and pan). Really cool to zoom out and have the universe in your hands
• Controller laser cursor to interact with stuff
• Hover text shows up near controller
• Add soundtrack
• Menu button to toggle the control panel and reticles
• Remove unused components
• Change src/index.js to require directories all at once

Would be nice later to:

• Use https://www.npmjs.com/package/aframe-state-component
• Be able to reset camera scale
• Preload the textures for the star detail dashboard to remove the frame drop

[flimshaw]

Hey @ngokevin, thanks so much for all this work. I gave it a try over here and there's a few features that break in browser mode, so I went ahead and just deployed your branch as its own subdomain on the site. You can check it out at http://vive.uptherevr.com/ and see if it works! Can't wait to try it out on the vive! If it works for you, please lmk and I'll put a new link on the homepage to it.