Remove unused bufferutil dependency

[webmaster128]

bufferutil pulls in node-gyp-build, which is for building native code. Most likely we don't want any of those in here.

It was added in #27. Was that on purpose?

[msteiner96]

Hmm when building the umd bundle.js I get Module not found: Error: Can't resolve 'bufferutil' without it :/

[webmaster128]

Can you try to move it from dependenvies to devDependencies? Then apps uing this package don't pull in the dependency.