Create helper for streaming file

[rmariano]

Helper object that will yield the contents of the file reading by a given buffer size.

Conditions:

• A file-like object
• Context manager, making sure the file is closed upon completion.
• Iterable

pseudocode:

with IterableFile('/tmp/foo/bar') as streamed_file:
     for chunk in streamed_file.stream(buffer_size=1024):
             print(chunk)