Fixes #272 Refactors slice_success and slice_error

The only calls to slice_success were the remove_item and remove_item_by_uuid methods in the slices. slice_success has been removed and the slices have been refactored to print the result to the console.

slice_error is only called from the slice_call method in slice.rb.  This method has been cleaned up to remove unnecessary mk_* references.  Additionally, error logging has been corrected to only log the error once, vice twice for standard errors.

Fixes #272