Fixed promises handling in Worker.prototype._workStart function.
Fixed _workStart annotation.
Fixed success determination in _workFinish.
Merge pull request #6 from lbeschastny/promises-fix

Jobs not failing on When.reject new Error
Fixed lastError for wrapped errors.
Merge pull request #10 from lbeschastny/job-last-error-message

Fixed lastError for wrapped errors.
Merge branch 'master' into reliable-queue

* master:
  Fixed lastError for wrapped errors.
  Fixed success determination in _workFinish.
  Fixed _workStart annotation.
  Fixed promises handling in Worker.prototype._workStart function.