Sanitize OAI endpoint links / UI enhancement

[Oliver Schonefeld]

The center registry should story only base URI for OAI provider, i.e. without query strings.

Instead if "http://repos.ids-mannheim.de/oaiprovider?verb=Identify" is should sanitize the value to "http://repos.ids-mannheim.de/oaiprovider"

Rationale: tools don't need to worry about stripping the query strings, when they query the center registry for OAI endpoints; the query string "verb=Identify" is already part of the OAI protocol and needs to be changed if a client wants to perform harvesting.

Furthermore, the center registry should provide the plain base URI of the endpoint, but could also provide links to endpoint information (labeled "Identity"; "?verb=Identify" appended to base URI) or supported metadata formats (labeled "Metadata formats"; "?verb=ListMetadataFormats" appended to base URI, etc.

Minor bug: there is a stray "<" after the table of OAI endpoints in the HTML view.

Does an URI exists for the REST interface, that generates a list of available ORI providers? If not, that would also be a nice feature.

[Sander Maijers]

​https://centres-staging.clarin.eu:4430/oai_pmh

REST API v2 example:
​https://centres-staging.clarin.eu:4430/api/model/OAIPMHEndpoint