Making 'segue' available in global scope

Hi @cheunghy, first off thanks for writing this plugin. You saved me from writing this on my own. 

I have been trying to use this with Cordova 3.5.0, and it appears that the 'segue' variable wouldn't get defined even after the plugin is loaded.

Here I made two fixes so that this plugin is automatically assigned to the window.segue variable once loaded by Cordova.