add publicationInfo element

add support for optional publisher info for federation
if publisher is set then generated metadata for federation (not export one) 
under md:EntitiesDescriptor  will contain 
<md:Extensions><mdrpi:PublicationInfo creationInstant="DATETIME_OF_GENEREATION" publisher="PUBLISHER_VALUE"/></md:Extensions>

after update you need to run standard procedure to update db schema (doctrine-cli)