implements configuration class, with unit tests

Unit tests can now be run using `python setup.py test`
- [x] `python setup.py test`
- [x] `conda build` with `run_tests.py`
- [x] root
- [x] material
- [x] image_series
- [x] image_series:file
- [x] image_series:images
- [x] image_series:omega
- [x] detector
- [x] detector:pixels
- [x] find_orientations
- [x] find_orientations:orientation_maps
- [x] find_orientations:seed_search
- [x] find_orientations:omega
- [x] find_orientations:eta
- [x] find_orientations:clustering
- [x] fit_grains
- [x] fit_grains:tolerance
- [x] find-orientations script uses config
- [x] extract_g_vectors uses config
- [x] fit-grains script uses config
- [x] logging