Upgrade to 4.0.0-pre.alpha.3

[rmseifried]

Upgrading core software to 4.0.0.-pre.alpha.3 and adding extra customizations:

• update field names to match new Aardvark terms
• update blacklight gem in order to for the split map view to work on a search page
• change formatting of 'GeoData' in header
• increase size of bounding box on home page
• customize facet display on search page and show page
• change sort order to alphabetical (by index) for Year [defaults low to high, can't sort any other way], Access, Resource Class, and Theme [and upped limit from 8 to 20]
• update test records: new to-be-approved terms in dcat_theme_sm, deleted dct_subject_sm