Event plugin addons with fix to make sure touch events are enabled

This includes #1170 changes and fixes #1619

If I'm opting into `React.addons.injectTapEventPlugin()` it should be implied that I want touch events enabled. So I just call `React.initializeTouchEvents(true)` in `TapEventPlugin.js`.

Created a [testcase](http://jsbin.com/roxat/9/edit) with a custom build based on this PR that works as expected.