Styling and layout updates to Admin/Curation pages

Fixes #642 

This pull request includes a bunch of commits but each is pretty minor, mostly just wording changes and minor CSS adjustments for most of the Admin/Curation pages. I did have to add a class to a couple of divs for styling purposes, but those seemed like reasonable classes to add.

Screenshots of how pages look after these updates:

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![administration_-_import_export___maps_of_africa__an_online_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2737932/27be1c28-c684-11e3-9120-11303091d049.png)

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![administration_-_appearance___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2737934/2e9a840a-c684-11e3-9d5c-b9ea064f4bd5.png)

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![curation_-_feature_pages___default_exhibit_-_blacklight 2](https://cloud.githubusercontent.com/assets/101482/2737940/48ed0986-c684-11e3-94e6-ff94d8a21ccd.png)

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![curation_-_tags__span_class__label_label-default__5__span____default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2737941/4d0e1032-c684-11e3-87dd-2785b25bc83e.png)

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![curation_-_dashboard___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2737953/89ad875c-c684-11e3-8e48-0623c15c87da.png)

<hr />
![curation_-_metadata___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2737971/f90efb3a-c684-11e3-8034-f3836b0f7d75.png)

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![administration_-_site_administration_-_users___default_exhibit_-_blacklight](https://cloud.githubusercontent.com/assets/101482/2737997/37fa88b4-c685-11e3-872c-4099c08ff4a6.png)