Fix undefined values in some core attributes for gen scripts
requested to merge github/fork/stavamichal/fixUndefinedValueInCoreAttributesInGenScripts into master
Created by: stavamichal
- there is a new behavior of retutning core attributes from perun RPC, now we get UNDEF for null value in core attribute
- for this reason we need to change behavior of working with core attributes in some gen scripts
- mainly problematic attributes are user attributes (first_name, last_name, middle_name, title_before, title_after)
- every service has it's own way how to work with undefined values in these core attributes