Unpin oauth2client after 1.4.4 release.
Merge pull request #415 from tseaver/unpin-oauthclient2-after-1.4.4-release

Unpin oauth2client after 1.4.4 release.
Add copyright and license headers
Merge pull request #416 from silvolu/copyright-headers

Add copyright and license headers
Integrating implicit credentials into dataset.