Flyers: Custom messages and larger byline image at wide breakpoint

Flyers now have a custom 'Read more' message for galleries and podcasts.

![screen shot 2014-12-19 at 11 23 30](https://cloud.githubusercontent.com/assets/2236852/5503684/e0334f22-8771-11e4-9e04-cada5e7ac16d.png)
![screen shot 2014-12-19 at 11 21 43](https://cloud.githubusercontent.com/assets/2236852/5503688/ef04f96a-8771-11e4-8a92-425169ccea1c.png)

Also increased the size of the byline image:

Before:
![screen shot 2014-12-19 at 11 21 35](https://cloud.githubusercontent.com/assets/2236852/5503691/fe18af5a-8771-11e4-94c0-f2fbd9a82c91.png)

After:
![screen shot 2014-12-19 at 11 21 25](https://cloud.githubusercontent.com/assets/2236852/5503694/0c19fbf4-8772-11e4-8984-d337d5f6923a.png)