relax sidekiq requirements to work with 2.17.0
Merge pull request #60 from musicglue/sidekiq-2.17.0

relax sidekiq requirements to work with 2.17.0
Bump to v0.5.0.
change 'Retrying in 5 seconds' to debug from warn
Merge pull request #61 from barelyknown/debug-retry-msg

change 'Retrying in 5 seconds' to debug from warn
Merge remote-tracking branch 'upstream/master'