Add KeyValue model

lib/keyvalue-model.js

@@ -0,0 +1,60 @@
+// Copyright IBM Corp. 2014,2016. All Rights Reserved.
+// Node module: loopback
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+/*!
+ * Module Dependencies.
+ */
+
+module.exports = KeyValueModel;
+
+var Model = KeyValueModel;
+
+function Model(registry) {
+  this.registry = registry;
+}
+
+// Static
+
+Model.get = function get(key) {
+  // ret val by key
+}
+
+Model.expire
+Model.expires = function() {
+  // ret remaining ttl/expires time
+}
+
+Model.delete =
+Model.remove = function(key) {
+  // del val by key
+}
+
+Model.set = function get(key) {
+  // set val by key
+}
+
+Model.touch = function touch(ttl) {
+  // renew ttl to given ttl, use now if ttl is not given
+}
+
+// Instance
+
+Model.prototype.delete = function() {
+}
+
+Model.prototype.get = function() {
+  // use id from inst to ret latest ver from backend
+};
+
+Model.prototype.getExpirationTime() {
+  // return expiration time (UTC timestamp)
+};
+
+Model.prototype.set = function(ttl) {
+  // use id from inst and call touch for the instance
+};
+
+Model.prototype.touch = function() {
+};