Creates config options for policy.json paths

Removes unsused "path" parameter from rbac_policy_parser.py.
Allows for configuration of policy.json paths by service for
Cinder, Glance, Keystone, Neutron, and Nova.

Change-Id: Ifb386511fd533d587d99de6585ddb78bc17cbc94
diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index b532d63..e342dd8 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -50,3 +50,13 @@
     # not found in the policy.json. Otherwise, they throw a
     # skipException.
     strict_policy_check = False
+
+    # The following config options set the location of the service's
+    # policy file. For services that have their policy in code (e.g.,
+    # Nova), this would be the location of a custom policy.json, if
+    # one exists.
+    cinder_policy_file = /etc/cinder/policy.json
+    glance_policy_file = /etc/glance/policy.json
+    keystone_policy_file = /etc/keystone/policy.json
+    neutron_policy_file = /etc/neutron/policy.json
+    nova_policy_file = /etc/nova/policy.json