Use auto_stub.TestCase.mock instead of mocking manually.
Use auto_stub.TestCase.mock instead of mocking manually.

It results in much cleaner code.

R=vadimsh@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/23089006

git-svn-id: d5a9b8648c52d490875de6588c8ee7ca688f9ed1@218039 0039d316-1c4b-4281-b951-d872f2087c98

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py