Support .body_stream in addition to .body.

This is specifically to support multi-part posts with things like
the multipart-post gem. Although it uses Net::HTTP because it utilizes
the body_stream method instead of body it was not previously working.
Merge pull request #49 from adamcrown/body_stream_support

Support .body_stream in addition to .body in Net::HTTP
Update change log for latest bugfixes
Bump version for bugfix