Implemented autoresize_full_height setting

This change introduces a new setting ```autoresize_full_height``` with these effects:

1. Automatically resize the editor's height between ```autoresize_min_height``` and the browser's window ```-20px```.
2. Automatically scroll the browser window if the editor would be expanded below the page fold.

So you always have the maximum size of your browsers window available for editing while being able to use all editor controls.

## Old behavior

![old](https://cloud.githubusercontent.com/assets/229567/3802760/d8e4114a-1c12-11e4-814f-7bf44377a78a.gif)

## New behavior

![new](https://cloud.githubusercontent.com/assets/229567/3802764/e3a18f22-1c12-11e4-84a4-b8b611a4b4c1.gif)