Added data streaming for blob files

There's limit to the size of data returned by child_process.exec(), which according to the docs, is 200k. Which means, if a file is greater than that, it'll simply not return the latter parts of the file.

I added a dataStreaming() to blob that returns a stream that you can use to get the data. However, I didn't know if it was better to return a stream, or to make a callback that returned chunks. I can modify it to do that, if you think that'd be easier for people to use.

Also, can you turn on issues section on your repo? It makes it easier for people(me) to bring up issues or discuss design before writing the code, so I don't do unnecessary work.