Handling of sub/filtered catalogs should be improved

[bryanrcarlson]

A lot of cleanup can be done with how sub-catalogs (aka filtered catalogs) are handled.

• URL should be more like an rest api; /catalog/{zoneName} should be something like /catalog/zones/{zoneName}
  • Issue Clickable Keywords #71 is related: url should be something like /tags/{tagName}
• Page header can be improved. "Work Zone Catalog" seems awkward. Maybe something like: "Catalog filtered by zone: Work". Probably better options than this.
• There's a lot of code copy/pasted for these filtered catalogs; see ZoneCatalogMetadataViewer, ProjectCatalogMetadataViewer, CatalogMetadataViewer (and soon TagMetadataViewer). Figure out a way to unify this. Create single component with parameters for what's being filtered? Pass a linq function to component?