Updated README.me - mention ActionMailer setting
Updated README.me - mention ActionMailer setting

Added to the documentation that a default ActionMailer 
delivery_method must be set for emails to be sent. 
Added instructions for it.
powershop/exception_notification,powershop/exception_notification,eitoball/exception_notification,DennisSchmidt/exception_notification,Axxiss/exception_notification,Aschen/exception_notification,wireframe/exception_notification,smartinez87/exception_notification,sparkgene/exception_notification,trevorturk/exception_notification,toshimaru/exception_notification,toshimaru/exception_notification,Aschen/exception_notification,lingceng/exception_notification,powershop/exception_notification,sparkgene/exception_notification,sparkgene/exception_notification,Axxiss/exception_notification,DennisSchmidt/exception_notification,Aschen/exception_notification,DennisSchmidt/exception_notification,wireframe/exception_notification,trevorturk/exception_notification,eitoball/exception_notification,lingceng/exception_notification,wireframe/exception_notification,trevorturk/exception_notification,smartinez87/exception_notification,Axxiss/exception_notification,lingceng/exception_notification