Remove page options and improve layout and styling of curation pages

Fixes #599 

This set of commits involves minor styling and layout adjustments to several Curation pages, based mostly on removing the page options from the feature and home page items panels, but also includes other styling updates. I removed two large tests (sorry!) that are no longer needed now that there are no page options in the Curation section.

Here are how the affected pages look with the updates in this pull request:

Search facets:

![curation_-_search_facets___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2621444/dc934076-bc55-11e3-99ba-e73cbef48d89.png)

Browse categories:

![curation_-_curation_-_browse___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2621452/eb37142c-bc55-11e3-9167-79fb9fe8705f.png)

Feature pages:

![curation_-_feature_pages___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2621455/f95b8dc6-bc55-11e3-8fb5-d17bfda66c6c.png)

About pages:

![curation_-_about_pages___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2621456/fe497672-bc55-11e3-9b48-b229fe8d9c58.png)