Build normalized, hook-internal representation of policy mapping
by performing a non-destructive parse of `sails.config.policies`

@returns {Object} mapping
@api private
function () {
            var mapping = { };
            _.each(sails.config.policies, function (_policy, controllerId) {

                // Accept `FooController` or `foo`
                // Case-insensitive
                controllerId = util.normalizeControllerId(controllerId);

                // Controller-level policy ::
                // Just map the policy to the controller directly
                if (!util.isDictionary(_policy)) {
                    mapping[controllerId] = policyHookDef.normalizePolicy(_policy);
                    return;
                }

                // Policy mapping contains a sub-object ::
                // So we need to dive in and build/normalize the policy mapping from here
                // Mapping each policy to each action for this controller
                mapping[controllerId] = {};
                _.each( _policy, function (__policy, actionId) {

                    // Case-insensitive
                    actionId = actionId.toLowerCase();

                    mapping[controllerId][actionId] = policyHookDef.normalizePolicy(__policy);
                });
            });

            return mapping;
        }