extension(storidge): add Storidge extension (#1581)

app/services/extensionManager.js

@@ -0,0 +1,36 @@
+angular.module('portainer.services')
+.factory('ExtensionManager', ['$q', 'PluginService', 'StoridgeManager', function ExtensionManagerFactory($q, PluginService, StoridgeManager) {
+  'use strict';
+  var service = {};
+
+  service.init = function() {
+    return $q.all(
+      StoridgeManager.init()
+    );
+  };
+
+  service.reset = function() {
+    StoridgeManager.reset();
+  };
+
+  service.extensions = function() {
+    var deferred = $q.defer();
+    var extensions = [];
+
+    PluginService.volumePlugins()
+    .then(function success(data) {
+      var volumePlugins = data;
+      if (_.includes(volumePlugins, 'cio:latest')) {
+        extensions.push('storidge');
+      }
+      deferred.resolve(extensions);
+    })
+    .catch(function error(err) {
+      deferred.reject({ msg: 'Unable to retrieve extensions', err: err });
+    });
+
+    return deferred.promise;
+  };
+
+  return service;
+}]);