Complete rewrite of the DARIAH-SP sample app and libraries (v2.0-dev)

The former and still used libraries are tagged as v1.4 and discontinued


## Important entry points

* Enable configuration in SecurityConfig
* SAMLMetadataController allows web access to SAML metadata
* AuthInfoHandlerInterceptor puts auth information in every model (through AuthInfoConfigurer)
* DefaultFiltersConfigurerAdapter for central logout and callback
* GlobalMethodSecurityConfig for method security (annotations)
* SecurityConfigurerAdapter for path and expression based security