remove sucker punch

sucker punch cannot be used in Resque jobs or other processes that are
not long-lived.  The only way to disable it is to turn on "testing mode"
for sucker punch, which is not ideal.

For now, leaving the question of how to send these messages in the
background unanswered.
documentation
Merge pull request #4 from stitchfix/remove-sucker_punch

Remove sucker punch