Added error handling when job fails permanently and failure callback raises an exception
Resolved merge conflicts with changes in upstream repo's master branch
Fixed Rubocop offenses with code introduced in my pull request
Changed usage of Logger::ERROR to 'error' within Delayed::Worker#failed
Merge pull request #661 from denisahearn/master

Added error handling when job fails permanently and failure callback rai...
Update simplecov dependency to >= 0.9
Ignore failure of Rubinius 2 builds