* Created test for get_policy with AWS managed policy.
* Created failing test for get_policy_version with AWS managed policy.
* Updated AWS managed policies.
* Fixed failing tests.
* Fixed trying to compare datetime with string in test case.
* Fixed CreateDate of AWS managed policies overwritten by their version's CreateDate.
* Fixed and improved tests for managed AWS policies.
* Added test for AWS managed policy with v4 default version.
* Fixed not correctly returning dates for AWS managed policies.
