CuPy issues in `test_ccdproc`

[mwcraig]

• test_subtract_overscan_model: modeling converts to numpy array
• test_trim_with_wcs_alters_wcs: wcs apparently converts to numpy also...
• test_unit_mismatch_behaves_as_expected: something about IrreducibleUnit and << operator -- this converts to numpy
• test_flat_correct_data_uncertainty: Still using np_array in this test function
• test_catch_transform_wcs_warning: same as test_trim_with_wcs_alters_wcs
• test_block_reduce: nddata/compat converts mask to numpy array (which I guess I knew)
• test_block_average: same as block_reduce
• test_block_replicate: same as block_reduce
• test_cosmicray_median_does_not_change_input: same as test_trim_image_fits_section CHECK BECAUSE THIS SHOULD BE FIXABLE
• test_cosmicray_lacosmic_does_not_change_input: Quantity numpy conversion; also watning about copy keyword
• test_wcs_project_onto_same_wcs: same as test_trim_with_wcs_alters_wcs
• test_wcs_project_onto_same_wcs_remove_headers: same as test_trim_with_wcs_alters_wcs
• test_wcs_project_onto_shifted_wcs: same as test_trim_with_wcs_alters_wcs
• test_wcs_project_onto_scale_wcs: same as test_trim_with_wcs_alters_wcs -- comes up wcs_for_testing
• test_sigma_func_for_ccddata: astropy stats converts to numpy array