Make property pages in BioPortal directly accessible

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When navigating the property tree, one can click on a property to see its (basic) attributes, including its identifier. (Reference ncbo/bioportal_web_ui#50.) However, unlike in the class tree, the displayed URL in the browser doesn't change, and there appears to be no way to enter a URL to go directly to that property page.

The request is to provide a URL to go directly to every property page, and to make any existing PURLs for BioPortal properties resolve to the corresponding property page.