Make AverageAlgorithm require **any** inputs

Recent attempts to change the AverageAlgorithm to allow fewer than the full
complement of inputs when calculating a mutli-station average were thwarted
by the default can_produce_data() method in the parent Algorithm class, which
required all inputs to be present, when what we now want is **any** inputs to
be present.

geomagio/algorithm/AverageAlgorithm.py

@@ -6,6 +6,7 @@ from __future__ import absolute_import
 from .Algorithm import Algorithm
 from .AlgorithmException import AlgorithmException
 from ..ObservatoryMetadata import ObservatoryMetadata
+from .. import TimeseriesUtility
 import numpy
 import obspy.core
 
@@ -65,6 +66,24 @@ class AverageAlgorithm(Algorithm):
         self.min_count_end = min_count_end
         self.observatoryMetadata = ObservatoryMetadata()
 
+    def can_produce_data(self, starttime, endtime, stream):
+        """Can Produce data
+
+        By default require all channels to have data at the same time.
+
+        Parameters
+        ----------
+        starttime: UTCDateTime
+            start time of requested output
+        end : UTCDateTime
+            end time of requested output
+        stream: obspy.core.Stream
+            The input stream we want to make certain has data for the algorithm
+        """
+        return TimeseriesUtility.has_any_channels(
+            stream, self.get_required_channels(), starttime, endtime
+        )
+
     def check_stream(self, timeseries):
         """checks a stream to make certain the required data
             exists.