stream file upload

[oshanz]

by looking at the source code I saw that this gem read complete file before doing the upload and I'm worried how much memory this will acquire for large files.

fog-backblaze/lib/fog/backblaze/storage/real.rb

Lines 183 to 185 in f45d376

	if content.is_a?(IO)
	content = content.read
	end

any otherway to improve this, like using stream/chunked upload?