reduce: count_nonzero results in AttributeError on numpy arrays

[wctaylor]

While the numpy package has a count_nonzero function, it is not an attribute of numpy arrays. Not quite sure what the best way to fix this is.

Relevant processing configuration info

stages:
    - pulse_cleaning: fast_carpenter.Define
pulse_cleaning:
    variables:
        - S2pulse: pulse_classification == 2
        - nS2pulses: {reduce: count_nonzero, formula: S2pulse}
        - S2area: {reduce: sum, formula: S2pulse * xyz_corrected_pulse_area_all_phe}

Stack Trace:

Traceback (most recent call last):
  File "/global/common/cori/software/python/3.6-anaconda-5.2/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/mantichora/hubmp.py", line 251, in run
    self._run_tasks()
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/mantichora/hubmp.py", line 271, in _run_tasks
    result = task_func()
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/mantichora/main.py", line 18, in __call__
    return self.task(*self.args, **self.kwargs)
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/alphatwirl/concurrently/CommunicationChannel.py", line 16, in __call__
    return self.task(*self.args, **self.kwargs)
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/alphatwirl/loop/EventLoop.py", line 45, in __call__
    self.reader.event(event)
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/alphatwirl/loop/ReaderComposite.py", line 43, in event
    if reader.event(event) is False:
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/fast_carpenter/define/variables.py", line 73, in event
    mask=mask, reduction=reduction)
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/fast_carpenter/define/variables.py", line 148, in full_evaluate
    result = reduction(result)
  File "/global/homes/w/wtaylor/.local/cori/3.6-anaconda-5.2/lib/python3.6/site-packages/fast_carpenter/define/reductions.py", line 52, in __call__
    return getattr(array, self.method_name)()
AttributeError: 'numpy.ndarray' object has no attribute 'count_nonzero'

[kreczko]

Fixed in #144