Move granting authorities to Authentication Provider.
Add security role hierarchy

Determine Fedora web Service credentials based on granted authority. Externalize user configuration.
Replace XML with Java configuration
Externalize Mapping from Role to Fedora Credentials

All Fedora credential objects are instanciated via Bean definitions. The Mapping from user roles to Fedora credentails happens in the `fedoraAuthorityDetails` bean. This way, roles, mappings and credentials are fully customizeable.

Mappings and Bean definitions can be overridden in a custom Bean XML file, that gets loaded from the ${qucosa.webapi.home}/config directory. This environment variable must be set when the servlet container is running the application.
Merge branch 'auth-conf'