PR for _sass branch

This branch is now ready for prime time. Thanks to all involved:
@gregrickaby @bradp @hugobaeta @obenland @sabreuse @MichaelArestad 
(and anyone else involved - you rock, thanks!)

Relates to: #548 
```scss
.format-aside .entry-title {
  .blog &,
  .archive & {
   display: none;
  }
}
```