Provide the ability to remove a role

[mkimberlin]

Currently, you can create and edit roles, but they can never be removed. So, effectively, once you increment the number of roles, you are there forever. We need to add the ability to remove non-required roles.

Acceptance criteria

• There exists a simple mechanism for initiating the removal of a role on the ADMIN->Roles page
• Initiating removal results in confirmation prompt before continuing
• Removing the role removes all membership information from the DB
• The mechanism for initiating removal of a role is not available (not visible or disabled) if the role is one of the currently required roles:
  • ADMIN
  • MEMBER
  • PDL