gracefully handle missing coveralls gem
gracefully handle missing coveralls gem

If we do not have coveralls installed, we should be able to continue
with the rest of the test suite.

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