extract user_is_admin(user) as a function

* does both `user.is_current_user_admin()` and `oauth.is_current_user_admin()`
* probably should be somewhere else?
make test pass after oauth merge

* need to logout OAuth user when checking auth
  * by default oauth recognizes as 'example@example.com' in dev mode.
* test_handlers.RevisionTest didn't have `self.testbed.deactivate()`
* lot of tests didn't have `self.testbed.init_user_stub()`
add more powers to run_tests

1. can run any kind of names:

		python run_tests.py lib/google-app-engine tests.test_handlers
		python run_tests.py lib/google-app-engine tests.test_handlers.WikiPageHandlerTest
		python run_tests.py lib/google-app-engine tests.test_handlers.WikiPageHandlerTest.test_post_new_page_should_fail_if_user_is_none

2. can run any combination of test suites:

		python run_tests.py lib/google-app-engine
			tests.test_handlers.RevisionTest
			tests.test_handlers.WikiPageHandlerTest.test_post_new_page_should_fail_if_user_is_none
test behavior for current user and is_admin_user

they're actually scattered away, for now.

  * `views.WikiPageHandler._get_cur_user`
  * `models.is_admin_user`

probably put it in one place...
Tweak acl checking order to improve performance
Clean up code to follow PEP8
Minor tweaks

*   Make 'comment' field optional
*   Use per-request cache in PUT and DELETE
Remove comment and revision field in test cases
Use PUT instead of POST
Fix typo
Make movies on vimeo.com embeddable
Fix invalid link in template
Fix invalid link in template
Fix invalid link in template
Fix errors in human readable strings in schema definitions
Fix error in schema index updating
Use put_multi when create new schema index
Make comment parameter in Model.update_content() optional
Allow to use yaml to specify schema properties
Respond with HTTP 303 for PUT request