Search results visual improvements & remove table default styles

The Google Custom Search widget uses tables for layout, and our default styles had an influence on its appearance.

- [new] Use our type scale for headings in search results
- [fix] Remove some unused styles and document some of the overrides for Google Custom Search
- [fix] magnifier icon is shown at native size (13x13px), now looks sharper
- [fix] Remove table default styles (I tested all pages where we have tables and added fixes where needed)

## Before

![screen shot 2014-03-12 at 18 50 20](https://f.cloud.github.com/assets/85783/2401527/4a029f90-aa17-11e3-89b3-c37816273ab7.PNG)


## After

![screen shot 2014-03-12 at 18 50 38](https://f.cloud.github.com/assets/85783/2401525/46f19a2c-aa17-11e3-9f3f-3540a195d9cc.PNG)

![ ](http://24.media.tumblr.com/8ec84c5bf7a03908287fe25b58aed58c/tumblr_n0lpulQw3x1siq7iyo2_250.gif)