Provide a generated id for every search field

Needed to use the "for" attribute of the <label> tag
Integrate prototype advanced search styling
Fix overlap issues with typeahead, advanced search, and map controls
Use the same template for missing searches and normal searches

Note: This requires that the field's data_type be overriden to 'bool'
Fix input width in advanced search
Add ISNULL predicate.

Replaces the MISSING search_type used in advanced search
Added JS test for search.buildElems
Stop trying to capitalize lowercase model names for safe_get_model

It's crazy to capitalize "mapfeature" and try to load the "MapFeature"
Python class.

Instead, require every use of the "create" and "search" templatetags
to use a case-sensitive model name.

The model names are still lowercased before being added to the DOM
though :(