Add documentation about setting images and custom views.

I __totally__ added an "image" to the ASCIIArt menu in the readme :grin: 

![screenshot 2014-07-24 08 23 12](https://cloud.githubusercontent.com/assets/139261/3687809/c940fa3e-132d-11e4-92ca-849726375510.png)

![high_five_stephen_colbert](https://cloud.githubusercontent.com/assets/139261/3689231/341915fc-133e-11e4-87e2-6b0f37f32e70.gif)