Refresh before request if neccesary
Add revokeCredentials() for easier revokeToken
Clean up tests
Expires_in is in seconds
Ensure that expiry_date is being set properly
Build multipart only when resource and media body provided
Remove expires_in and simplify shouldRefresh logic
Merge pull request #235 from ryanseys/refresh-before

Refresh before request if neccesary and multipart only when resource and media body specified