bug solved, now check to see if the type is NoneType
update bugs
removed unused field
added defaults="" in fields that are not required, this avoids possible
	errors with types (NoneType, Unicode), for expample when a survey
	is read from xml file, before added in the ddbb type "NoneType" in
	the empty fields
deleted garbage
added code html and view to export xml survey
test to export/import xml survey
added: import survey xml to bbdd