Adds grunt-phonegap to automate build process.

It adds [grunt-phonegap](git@github.com:logankoester/grunt-phonegap.git) with default configurations.
This will make so everyone can easily deploy on devices with `grunt build:android` and `grunt build:ios` because everything needed for it would be here.

What needs be done after this:

1. Change the config.xml file for the currently being used.
2. Move icons and splash screens to this repo and link them in the Gruntfile.
3. Setup some more configuration.

I would do this things but I don't have those files.