Undesired xml:lang on some fields

[joachimnielandt]

The following issue is a result of a check performed by @CMath04 during the last sprint. To be concluded / fixed, I'm creating a relevant issue to track progress whenever we can pick this up.

xml:lang is automatically added on non multilingual field but should
not

• vcard:organization‐name ⇒ maybe should be multilingual in the
  XSD instead ?
• vcard:street‐address ⇒ maybe should be multilingual in the XSD
  instead ?
• vcard:country‐name ⇒ maybe should be multilingual in the XSD
  instead ?