TST: test both pysatCDF and cdflib

[jklenzing]

Updates suggested for pysat/pysat#102.

• Adds second round of tests to load with both pysatCDF and cdflib.
• Fixes a bug where cdflib cannot be accessed in omni data

Requires pysat develop and pysatCDF RC. CI tests expected to fail.

[jklenzing]

Local tests pass using above branches. Requires a slight modification to pysat as outlined in #172

[rstoneback]

Local tests pass for me as well, except for Gold, but that is already handled elsewhere. I ran tests with the load_meta_proc branch.

[jklenzing]

Note to self: running additional tests for cdf load can be streamlined in the next pysat release using the _test_load_opt notation.

[jklenzing]

Doing a manual install of pysatCDF works, but this branch still requires changes in the develop branch of pysat.

[rstoneback]

Thanks for advancing things. Great to hear manual install works.

[jklenzing]

Note to self: prioritize pysat/pysat#85 once pysat 3.0.2 is released. merge those back here to streamline.

[rstoneback]

I'm ok with merging this into pysat/pysat#102 whenever ready. They are in the same testing ⛵