Added /ws endpoint and access to programmatic clients in BasicAuth

gms/src/main/java/it/inaf/ia2/gms/authn/SecurityConfig.java

.../it/inaf/ia2/gms/authn/WebServiceAuthorizationFilter.java

...ain/java/it/inaf/ia2/gms/controller/GroupsController.java

...java/it/inaf/ia2/gms/controller/WebServiceController.java

...src/main/java/it/inaf/ia2/gms/persistence/ClientsDAO.java

gms/src/main/java/it/inaf/ia2/gms/persistence/GroupsDAO.java

.../java/it/inaf/ia2/gms/persistence/model/ClientEntity.java

gms/src/main/java/it/inaf/ia2/gms/service/GroupsService.java

gms/src/main/resources/sql/init.sql

...inaf/ia2/gms/authn/WebServiceAuthorizationFilterTest.java

.../test/java/it/inaf/ia2/gms/persistence/GroupsDAOTest.java

...inaf/ia2/gms/persistence/NestedGroupsIntegrationTest.java