Move sessionStorageModule into main storageModule

Fixes #586

 - add get/saveSessions to main storage module
 - handle storage modules without those functions
 - store .session file in userDir

red/api/auth/tokens.js

@@ -0,0 +1,62 @@
+/**
+ * Copyright 2015 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+
+var when = require("when");
+
+function generateToken(length) {
+    var c = "ABCDEFGHIJKLMNOPQRSTUZWXYZabcdefghijklmnopqrstuvwxyz1234567890";
+    var token = [];
+    for (var i=0;i<length;i++) {
+        token.push(c[Math.floor(Math.random()*c.length)]);
+    }
+    return token.join("");
+}
+
+
+var storage;
+var sessions = {};
+
+module.exports = {
+    init: function(_storage) {
+        storage = _storage;
+        return storage.getSessions().then(function(_sessions) {
+             sessions = _sessions||{};   
+        });
+    },
+    get: function(token) {
+        return when.resolve(sessions[token]);
+    },
+    create: function(user,client,scope) {
+        var accessToken = generateToken(128);
+        var session = {
+            user:user,
+            client:client,
+            scope:scope,
+            accessToken: accessToken,
+        };
+        sessions[accessToken] = session;
+        return storage.saveSessions(sessions).then(function() {
+            return {
+                accessToken: accessToken,
+            }
+        });
+    },
+    revoke: function(token) {
+        delete sessions[token];
+        return storage.saveSessions(sessions);
+    }
+}
+