Make it easier to use by showing how to load a buffer

[sole]

Newcomers might have no clue of how to load a buffer (what is a buffer EVEN?) so that should be demonstrated in the example instead of leaving it up as homework

[sole]

Ways to load a buffer:

• load a sample with XMLHTTPRequest, then decode the binary data with the audioContext's decodeAudioData method
• if using browserify, inline the binary data with browserify transforms as demonstrated in the drum-machine demo

any other ways?