finished Circle class and tests..
Merge branch 'master' of https://github.com/UWPCE-PythonCert/IntroToPython
Added reflection
Merge pull request #79 from voite1/master

Added reflection
Merge branch 'master' of https://github.com/UWPCE-PythonCert/IntroToPython
Finished the circle module.  Added some assertions in the @radius.setter and @diameter.setter to check that the radius and diameter of the circles were valid at initialization.
The pytest testing module for my Circle class.  Does a bunch of tests.  Circle passes all of these.