Add the tool usgscsm_cam_test (#373)

* Add usgscsm_cam_test tool

* .gitignore: Do not ignore bin as there will be an executable there

* Flesh out a bit the proposed test tool

* usgscsm_cam_test: Finish loading functionality

* usgscsm_cam_test: Print note of failure if could not load a model.

* usgscsm_cam_test: Use the more generic CSM approach

* Add a test for the test program

* Move test