[tests] Base class for MDP algorithm tests
[tests] Base class for MDP algorithm tests

Add a base class that other classes for testing the MDP algorithms can
use it.

sawcordwell/pymdptoolbox,McCabeJM/pymdptoolbox,silgon/pymdptoolbox,silgon/pymdptoolbox,yasserglez/pymdptoolbox,McCabeJM/pymdptoolbox,yasserglez/pymdptoolbox,sawcordwell/pymdptoolbox