Merge pull request #1 from geoffjentry/master

Pull request to update to forks parent
Add ability to upload an image using 'statuses/update_with_media'
Refactored to use doAPICall once
Removed un-necessary multipart parameter

POST() uses by default multipart=TRUE and there is no no need for a
caller of doAPICall to change it.
Merge pull request #57 from ChristopherHackett/feature/statusesUpdateWithMedia

Feature/statuses update with media