Make DistributionPoint relative_name a set of NameAttribute (#3210)

* Add RelativeDistinguishedName class

* Make relative_name a RelativeDistinguishedName

DistributionPoint relative_name is currently a Name but RFC 5280
defines it as RelativeDistinguishedName, i.e. a non-empty SET OF
name attributes.  Change the DistributionPoint relative_name
attribute to be a RelativeDistinguishedName.
9 files changed