Add tests for loading JWST data

[drdavella]

This resolves #460.

[codecov[bot]]

Codecov Report

Merging #538 into master will decrease coverage by 5.26%. The diff coverage is n/a.

@@            Coverage Diff            @@
##           master    #538      +/-   ##
=========================================
- Coverage   64.16%   58.9%   -5.27%     
=========================================
  Files          39      26      -13     
  Lines        4956    4263     -693     
=========================================
- Hits         3180    2511     -669     
+ Misses       1776    1752      -24

Impacted Files	Coverage Δ
cubeviz/tests/helpers.py
cubeviz/tests/test_ui.py
cubeviz/setup_package.py
cubeviz/tools/tests/test_smoothing_gui.py
cubeviz/tests/__init__.py
...ubeviz/data_factories/tests/test_data_factories.py
cubeviz/tools/tests/test_collapse_cube.py
cubeviz/controls/tests/test_slice_controller.py
cubeviz/controls/tests/test_flux_units.py
cubeviz/tools/tests/__init__.py
... and 2 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 861d9d3...a7a0495. Read the comment docs.

[SaOgaz]

Hey @drdavella, I've got another cubeviz test file ready to go (already checked cubeviz can open it fine). Do you have time to add it to this PR or should I open a new issue for it?

filename: ditherunity_CLEAR_PRISM_M1_m1_noiseless_NRS1_modified_updatedHDR_fixintarget_s3d.fits

[drdavella]

@SaOgaz I added a new developer documentation section with instructions for testing. I also added some basic documentation about building the docs while I was at it.

[drdavella]

I'm pretty sure this is ready for final review and merge. I believe the reason the coverage has decreased for this PR is because I added a commit that removed the test files from coverage (which should have been the case to begin with). This means technically the coverage has gone down, but future PRs should be more accurate.