Added Area3DTests.cpp (#3216)

* Added BasisFunctionTests.cpp. Removed BasisFunction unit test and truthfile.

* changed expectedOutput values for some of the tests

* Made tests for Displacement.cpp using gtest. removed Displacement unitTest and truthfile.

* Added Area3DTests.cpp, removed Area3D truthfile and unit test.

* included TestUtilities.h for use with exception testing, added a test for teh Area3D '=' operator

* changed formatting to adhere to USGS coding standards

* re-addedd the unit test and truth file