Support multipart uploads (non-proxy only for now)
Merge branch 'master' into multipart-upload

Conflicts:
	CHANGELOG
No need to detect the MIME type of media uploads, sort OAuth params correctly
Fix documentation for return value of _buildMultipart
Force proxy for multipart base64
Merge branch 'multipart-upload'
Add section about media file uploads to README
No 2.3.4 release
Merge branch 'QA_2_3'
2.4.0
2.5.0-dev