Force the webview to be the screen size

This PR force the webview to be the screen size and prevent this kind of problems

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| ![screenshot_2014-12-22-18-42-18](https://cloud.githubusercontent.com/assets/13337/5531156/9fc32fde-8a0f-11e4-9cb5-38f1a1c34e75.png) | ![screenshot_2014-12-22-18-42-26](https://cloud.githubusercontent.com/assets/13337/5531157/9fc398e8-8a0f-11e4-8531-0edc3879065c.png) |

It also fix the https://github.com/aerogear/aerogear-android-cookbook/pull/26 problems when you use Facebook