Move upload method from Repository to Artifact.
Update docs for moving the upload method to Artifact.
Fix spelling of "instance" in descriptions.
Change argument order for backward compatibility.
Implement Repository.upload via Artifact.upload.
Move to_matrix_properties method to base class.
Fix extra space and document Repository.upload.
Remove extra whitespace.
Artifact.upload supports upload of any kind of IO object.
Merge pull request #22 from opscode/yzl/issue-18

Yzl/issue 18