Issues account creation

[olafveerman]

When creating a user (/user/add), the following issues were encountered:

• The help text "If you would like to change the password type a new one. Otherwise leave this blank." is slightly confusing as it is not possible to leave the field empty when adding a user
• The Roles checkbox + Account notification checkbox are reset to Administrator and Null on a validation error.
  To replicate:
  1. Add details about the user, leave password field empty
  2. Assign the moderator role
  3. Choose to notify the user about account creation
  4. Hit save