Decode the non-english username str to unicode

convert the non-english username str to unicode,
then the converted username can match the username from db.

Fixes bug #1221576

Change-Id: I9e5f941fe43f081d75750e3f4754e8beea8210db
Allow blank to email in user-update

User cannot set blank to email address when use "user-update".

This patch fixes this problem.

Change-Id: I3b9494a1c668358a529031c366c55b303f43c533
Closes-bug: #1226439
Merge "Decode the non-english username str to unicode"
Merge "Allow blank to email in user-update"