Remove old video plugin

- Will be using HTML5 video for iOS. Android may require
  a newer VideoPlayer plugin: http://bit.ly/1hlMEn2
Ignore platforms directory, remove builds from repo
Replace call to phonegap.js with cordova.js

- Seems that phonegap.js is deprecated in favor of
  the new cordova.js file as of at least version 3.0
Add device plugin

- Provides a device object - previously seemed to be a default,
  now is managed via:

  http://docs.phonegap.com/en/3.0.0/cordova_device_device.md.html