Make deck description scrollable (issue 1974)

*Squashed and rebased version of  #219*

It moves the deck description to the bottom of the deck info layout, and disables truncation of the deck description so that users can scroll to view the whole text. Solves [issue 1974](https://code.google.com/p/ankidroid/issues/detail?id=1974)

Unfortunately for very small screens, it may mean that scrolling is necessary to see *any* of the deck description, but for most screen-sizes it should not be a problem. See the below screenshot for an example of what I mean on QVGA (smallest Android screen size)

![scrollable description](https://f.cloud.github.com/assets/2818274/2470456/ffbf93f0-b012-11e3-8e71-da0b36e0b991.png)