Properly decode bytestring of shell output.
Remove unused mock import.
Add parameter for miminim interval seconds.

This paraemter adds the capacity to require a minimum number of seconds
between collections by pmort.  It defaults to just one second but could
be set as high as maximum interval seconds (it's undefined, currently,
if minimum is greater than maximum).
Add test for maximum load property.
Update setup classifiers.
Add test of linear timings.

The timings of the linear learner indeed match the expected outputs.