merovingian: pass gdk_dbfarm onto started mservers
merovingian: pass gdk_dbfarm onto started mservers

now that we do no longer use the monetdb5.conf file, make sure the
started mservers know where they should be doing their stuff (e.g. the
same place merovingian expects them to do it).

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb