Implement binary support for ios as well

[kevinmershon]

This featureset does a couple of interesting things that may not be obvious:

1. Instead of always reading up to a null terminator (e.g. strings), this version reads until the input stream doesn't receive any packet data.
2. Instead of passing chunked, escaped strings back to Javascript, we base64-encode from the native later and then use window.atob on invocation of the Javascript to decode, ensuring we can pass true binary data back.

Be sure to view the pull request with ?w=1 appended to the URL (to ignore whitespace changes).