Reduce duplicated code related to policies

This patch adds some logic that is currently duplicated throughout
Openstack. As part of this de-duplication, the patch also modifies
current implementation.

Major Changes:
    * check, set_rules, reset, init are now part of the Enforcer class
    * check was renamed into enforce
    * init was renamed into load_rules
    * It is now possible to load multiple files and have per instance
      rules instead of global rules.
    * There's a global instance of the Enforcer class that can be used as
      main enforcer.

        from openstack.common import policy
        ENFORCER = policy.ENFORCER
        ENFORCER.enforce(rule, target, creds)

Minor Changes:
    * Added do_raise to the enforce method
    * Enforcer instance is now passed to the Check call.

NOTE: If / once this patch gets in, I'll update other projects and port
them to the latest version.

Change-Id: Ife909bdf3277ef33c2fb1eae16ae261fa6374c63

1 files changed, 4 insertions, 0 deletions

diff --git a/tests/var/policy.json b/tests/var/policy.json
new file mode 100644
index 0000000..73730ae
--- /dev/null
+++ b/tests/var/policy.json
@@ -0,0 +1,4 @@
+{
+    "default": "rule:admin",
+    "admin": "is_admin:True"
+}