Fix bugs

• pan and swipe direction control not working
• panstart/panend and some other gestures warning

Fix bug:

• Fix babel-runtime dependency not found.

Main changes:

• Update webpack and the plugins to the latest.
• Change main file from index.js to index.min.js.
• Built-in babel and uglifying.

Fix bug:

• Some error in IE because of es6.
• v-hammer:pan.left.right can not use before. Users can use any directions in the modifiers, like something extreme: v-hammer:left.right.up.down