Release 6.20.0: Login servlet mapping is removed from servletmapping.properties

[changerequest]

The login servlet requires for new possible login methods additional configuration parameters. Those configuration parameters can be passed more easily if the login servlet is added through a BundleActivator and not by static initialization through a class loader.

The line

/ajax/login:com.openexchange.ajax.Login

is removed from the servletmappings.properties configuration file. The URL is now a Java string constant and the Servlet is added to the servlet container using a BundleActivator and the HttpService.