Add form to add contacts

Currently we don't have a form to add / delete / etc. contacts. In order to fill the stuff in from the current Tereno database, I need a mechanism to add contacts.

We currently don't have a full concept for this handling (I think to remember that UFZ wants them to be added as user log in; but this is not necessary the way for all the use-cases).

For now I just need a form to insert contacts. We may can take it out of the software later.