Fix UnicodeError when givenName or sn Shibboleth Header contains unicode chars

Shibboleth Header values like Nicol\xc3\xb2  raise UnicodeError evaluating fullname 
yeah.  It's surprising to me that you'd have to do this.  Especially because we're already including unicode codepoints in the tests.

Can you post a failing stacktrace?  Let's be sure that the fix is really appropriate.