Followed licensing guide from apache

Resolves dexie#596

NOTICE

@@ -0,0 +1,15 @@
+Dexie.js
+
+Copyright (c) 2014-2017 David Fahlander
+
+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.

src/Dexie.js

@@ -2,13 +2,14 @@
  * Dexie.js - a minimalistic wrapper for IndexedDB
  * ===============================================
  *
- * By David Fahlander, [email protected]
+ * Copyright (c) 2014-2017 David Fahlander
  *
  * Version {version}, {date}
  *
  * http://dexie.org
- *
- * Apache License Version 2.0, January 2004, http://www.apache.org/licenses/
+ * 
+ * Apache License Version 2.0, January 2004, http://www.apache.org/licenses/LICENSE-2.0
+ * 
  */
 
 import {

src/Promise.js

@@ -1,3 +1,7 @@
+/*
+ * Copyright (c) 2014-2017 David Fahlander
+ * Apache License Version 2.0, January 2004, http://www.apache.org/licenses/LICENSE-2.0
+ */
 import {doFakeAutoComplete, tryCatch, props, setProp, _global,
     getPropertyDescriptor, getArrayOf, extend} from './utils';
 import {nop, callBoth, mirror} from './chaining-functions';