Drop compatibility with old configuration style
Drop compatibility with old configuration style

Since rack middleware is now called ExceptionNotification::Rack instead
of ExceptionNotifier, upgrading from previous versions requires changes.
Then when upgrading, users will also have to upgrade configuration
options hash.

Aschen/exception_notification,smartinez87/exception_notification,lingceng/exception_notification,Axxiss/exception_notification,DennisSchmidt/exception_notification,toshimaru/exception_notification,powershop/exception_notification,lingceng/exception_notification,Axxiss/exception_notification,eitoball/exception_notification,DennisSchmidt/exception_notification,trevorturk/exception_notification,trevorturk/exception_notification,sparkgene/exception_notification,powershop/exception_notification,sparkgene/exception_notification,smartinez87/exception_notification,Aschen/exception_notification,powershop/exception_notification,toshimaru/exception_notification,wireframe/exception_notification,DennisSchmidt/exception_notification,wireframe/exception_notification,Axxiss/exception_notification,eitoball/exception_notification,wireframe/exception_notification,lingceng/exception_notification,trevorturk/exception_notification,Aschen/exception_notification,sparkgene/exception_notification