Make email addresses optional in external auth if email feature is turned off

Before this change, external auth such as Keystone would fail if a user without an email address tried to login, even if the email feature was disabled.

endpoints/api/superuser.py

@@ -210,7 +210,7 @@ class SuperUserList(ApiResource):
     'CreateInstallUser': {
       'id': 'CreateInstallUser',
       'description': 'Data for creating a user',
-      'required': ['username', 'email'],
+      'required': ['username'],
       'properties': {
         'username': {
           'type': 'string',
@@ -253,15 +253,15 @@ class SuperUserList(ApiResource):
 
     user_information = request.get_json()
     if SuperUserPermission().can():
-      username = user_information['username']
-      email = user_information['email']
-
       # Generate a temporary password for the user.
       random = SystemRandom()
       password = ''.join([random.choice(string.ascii_uppercase + string.digits) for _ in range(32)])
 
       # Create the user.
-      user = model.user.create_user(username, password, email, auto_verify=not features.MAILING)
+      username = user_information['username']
+      email = user_information.get('email')
+      user = model.user.create_user(username, password, email, auto_verify=not features.MAILING,
+                                    email_required=features.MAILING)
 
       # If mailing is turned on, send the user a verification email.
       if features.MAILING: