add deactivation email template and service operation
added a new controller providing a service operation for account deactivation
added a new controller providing a service operation for account deletion
abstract base class for account management controllers
replaced the abstract account management controller with a separate service class
return status 404 if the user to deactivate/delete could not be found
removed superfluous inheritance
Merge pull request #37 from osiam/osng-479

Osng 467/479: self administration API for account deactivation and deletion