Use `native-buffer-browserify`

Much faster buffer, backed with ArrayBuffer.
native-buffer-browserify: only support browsers with Uint8Array
3.0.0
Update native-buffer-browserify to 1.0

- Fix test failures caused by incorrect default param coercion on
`Buffer.toString`.
- Fix documentation to show support for all modern browsers, plus IE10+.
- Add Firefox support using ES6 Proxy (see rationale below).

Firefox ES6 Proxy Workaround
========================
Firefox does not allow augmenting "native" objects (like Uint8Array
instances) with new properties for some unknown (probably silly)
reason.  So we use an ES6 Proxy (supported since Firefox 18) to wrap
the Uint8Array instance without actually adding any properties to it.
3.1.0
Merge pull request #36 from feross/master

Use `native-buffer-browserify`