Cep17 implementation

Tests have been converted from previous classes.  Redundant tests eliminated due to elimination of redundant code in resource class hierarchy.  Rather than as a diff, reviewer(s) should focus on code quality and implementation of: Resource class, Material class, Composition class, ResTracker class, GenericResource class, compmath namespace, and MatQuery class.  There is a companion PR for cycamore.

For more information, see http://cyclus.github.io/cep/cep17.html.