Multiple Logos and Displaynames per entity

[baszoetekouw]

This is the Manage-part of OpenConext/OpenConext-engineblock#1338

We want to be able to show multiple entries in the WAYF for a single SAML entity. Specifically, that means that we need to be able to specify multiple Logos and OrganisationalDisplaynames in Manage for a single entity.

Also, we need to decide how to push this to EB.