Use `native-buffer-browserify` for fast Buffer (backed by ArrayBuffer)

Sending this over to add `native-buffer-browserify` and show how to fix the test failures on node 0.10 because of a bug in the `vm` module where it doesn't make `Uint8Array` available in the execution context. This appears to be fixed in Node 0.11.

(These changes might need to be moved into the 3.0 branch which @substack said he'll push tonight)