Adjust heading levels and style changes

Closes #217, #402 

* Added changes specified in #217 
* Modified/added tests to reflect changes
* Adjusted styles to main elements like facets, top menu bar etc. to match @jvine 's visual design

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![image](https://cloud.githubusercontent.com/assets/302258/3474873/7e39d028-02e9-11e4-959d-4d0221281e35.png)
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![image](https://cloud.githubusercontent.com/assets/302258/3474892/a2b47fde-02e9-11e4-98e0-a448f2a5cf8f.png)
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![image](https://cloud.githubusercontent.com/assets/302258/3474902/d2a9ca00-02e9-11e4-9b69-92ad922aa1c8.png)


@jkeck @mejackreed Added base styles here for `h1`, `h2` and `h3` from Jennifer's visual design page. These styles override bootstrap's values.