Make install required for tests

**Original report ([archived issue](https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-rendering/issues/7)) by Nate Koenig (Bitbucket: [Nathan Koenig](https://bitbucket.org/%7Bc862cdd9-fcc8-4419-9fc7-e20db14b8fcb%7D/)).**

----------------------------------------
Update the code/tests so that `make install` is not required.

This may only be true for optix tests.

Start by running the test suite without running `make install`, then identify which tests fail and whether the OptiX test setup is responsible. Review the test and build configuration involved; done means the affected tests pass directly from the build tree without requiring installation.

Written by the indexing model from the issue text.