basic keyboard shortcuts

Spacebar for play/pause, j/k keys for vim-style track skipping.
Also, added some missing "http:" to the beginning of a couple script URLs that was causing it to fail locally. Since you don't have https on microbeats.cc (I checked) this should have no effect on production.

Tested and working in Chrome. Probably want to test in IE before accepting, but I couldn't do this.

Tested:
Spacebar to play
Spacebar to pause
J & K to skip while playing
J & K to skip while paused