Prevent approval requestor role from being the only role assigned an account

Current Situation

The SourceForge thread Login failed after assigning the approval_requestor_role explains that an account can be assigned the "approval_requestor" role as the only role. This results in denial of access as the "approval_requestor" role does not offer login capabilities but is an additional role to specify for which operations the JS7 - Approval Process is triggered.

Desired Behavior

• The GUI should deny that the "approval_requestor" role is the only role assigned an account.
• The name of the "approval_requestor" role is arbitrary and is specified with the Settings page, section "joc".