This is a follow-up patch for https://review.openstack.org/#/c/258392/
That one added good unit test cases for various kinds of
allowe_origin like '*' or ''(empty). However, the result of handling
in Swift proxy will depend on strict_cors_mode option configuration.
This patch refactors the unit tests to split out for
strict_cors_mode = on/off and add some missing unit tests for
each case.
Change-Id: I55f7cd279436b5c9f71d81fecf06021380e35579
e15bceaa7e