Add Collection and SDR Mastheads

Closes #590

### Masthead for Collection Type: Digital Collection
![digi-coll-masthead](https://cloud.githubusercontent.com/assets/96776/4156552/731b9484-3475-11e4-8a5b-b0a49e0293e0.png)

### Masthead for SDR
![sdr-masthead](https://cloud.githubusercontent.com/assets/96776/4156551/7319d518-3475-11e4-8b06-88eee841d2c3.png)