Pre-filter search resource types

[winthropo]

Here are the values we can enable/disable:

All items
Archival Materials
Articles
Audio Visual
Bibliographic Data
Books
Conference Proceedings
Databases
Dissertations
Documents
e-Books
Games
Government Documents
Images
Journals
Legal Documents
LibGuides
Maps
Newspaper Articles
Patents
Programmed Texts
Rare Books
Reference Entries
Research Datasets
Reviews
Scores
Standards/Specifications
Statistical Data Sets
Statistics
Treaties
Updating Loose Leafs
Web Sites