Expand test suite

[jkwan2011]

With the completion of #10, we now have the ability to run tests using a generalized input. To expand the test suite:

• Create a loader for the heating data
• Add new tests of functionality (possibly derived from test_engine)
• Add more data from Steve's examples (add files and paths) and run tests

[axiomizer]

Test added to check the UA and standard deviation of UA. (PR #80)

Four more examples added (example 4, Breslow, Cali, and Feldman) and also added a check to make sure the correct balance point is found. (PR #86)