- Removes the use of the system current username as the default
  profile name in the account creation wizard, and also removes
  the insertion of "Jami account" as a profile name if the user
  clears the profile name text field.

- For accounts lacking profile name and registered name:
  - fixes the best name display in the account selection combobox
  - fixes the fallback avatar choice

Change-Id: If38d575274542bd59b11dac8a17d983edcbd266c