Can't handle binary data when using node

When getting binaries, the library uses `Blob` and `FileReader` to read the data (see [here](https://github.com/remotestorage/remotestorage.js/blob/master/src/wireclient.js#L99)).

Both these objects are not available in NodeJS.

I thought this could be easily fixed by requiring https://github.com/coolaj86/node-file-api in Node, but the [file for Blob](https://github.com/coolaj86/node-file-api/blob/master/Blob/Blob.js) is just empty and I didn't find any other replacement yet.