Allow both version of bold/italics, break, and underline in all quotes

Applies to https://github.com/GigaOM/gigaom/issues/5315

_Note there is a `<br>` after "viewpoints" in the images below as well (not really visible)._
### Pullquote:
![screen shot 2014-09-19 at 9 19 02 am](https://cloud.githubusercontent.com/assets/929375/4335767/f7f1b7fc-3fff-11e4-952c-835175a238df.png)
### Blockquote:
![screen shot 2014-09-19 at 9 22 39 am](https://cloud.githubusercontent.com/assets/929375/4335778/0e1ff4f8-4000-11e4-9532-88e6af589c88.png)
### And just to round it out, Quote:
![screen shot 2014-09-19 at 9 24 49 am](https://cloud.githubusercontent.com/assets/929375/4335809/5e44b2b6-4000-11e4-93c2-ae3db1589b81.png)