remove trailing white-spaces from app/models/mail_handler.rb

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11127 e93f8b46-1217-0410-a6f0-8f06a7374b81
Test fails when run at the beginning of the day.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11128 e93f8b46-1217-0410-a6f0-8f06a7374b81