Validate username with nodeprep
Validate username with nodeprep

This involves both ensuring that the username contains only valid characters, as well as checking that both username and XMPP node are unique

Kromey/akwriters,Kromey/akwriters,Kromey/fbxnano,Kromey/fbxnano,Kromey/akwriters,Kromey/akwriters,Kromey/fbxnano,Kromey/fbxnano