Add support for adding Client Certificates to access-lists

Client certificate support is added as a new separate type of option for
access-lists.

This commit is the support code to enable access-lists to contain
Client Certificate references.

backend/schema/endpoints/access-lists.json

@@ -142,6 +142,13 @@
 							}
 						}
 					},
+					"clientcas": {
+						"type": "array",
+						"minItems": 0,
+						"items": {
+							"type": "integer"
+						}
+					},
 					"meta": {
 						"$ref": "#/definitions/meta"
 					}
@@ -209,6 +216,13 @@
 								}
 							}
 						}
+					},
+					"clientcas": {
+						"type": "array",
+						"minItems": 0,
+						"items": {
+							"type": "integer"
+						}
 					}
 				}
 			},