add LDAP integr. test for receiving share candidates with group limitation

build/integration/config/behat.yml

build/integration/features/bootstrap/AppConfiguration.php

build/integration/features/bootstrap/BasicStructure.php

build/integration/features/bootstrap/CalDavContext.php

build/integration/features/bootstrap/LDAPContext.php

build/integration/features/bootstrap/ShareesContext.php

build/integration/features/bootstrap/Sharing.php

build/integration/features/bootstrap/WebDav.php

...d/integration/ldap_features/openldap-uid-username.feature