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
Changing auth to use implicit environment.
Removing superfluous patches in test_generate_signed_url_w_expiration_int.
Fix external links in navigation bar
Merge pull request #420 from silvolu/fix-nav-links

Fix external links in navigation bar
Changing description of GOOGLE_APPLICATION_CREDENTIALS.
Merge pull request #419 from dhermes/add-better-auth

Changing auth to use implicit environment.
Update encrypted key for regression tests
Ideas commit for better (implicit) auth story in datastore.

Also
- Integrates this idea into the datastore regression tests.
- Creates a (temporarily ignored) cyclic import
- Has an uncovered statement that confuses nosetests
- Implements a friendlier (more gcloud-node like) version of
  allocated_ids
- DOES NOT update CONTRIBUTING to explain change to regression
  tests or ditch unneeded helper / environ code for regressions
- Creates a datastore cleanup script for when tests get
  broken