leave units blank by default

[jchate6]

We should not autofill the brightness units. Users should have to fill this in themselves.
This will also hopefully mean that these values will not autofill in the JSON and text version.

Specifically, brightness_unit, limiting_brightness_unit, ra_error_units, and dec_error_units are an issue.

This is a function of how we do drop downs.
The best solution in my opinion is to leave all of these blank and un-validated unless the corresponding value is present.
i.e. there is no limiting_brightness_unit unless a limiting_brightness is supplied.

At the very least we should hide them from the text view.

[jnation3406]

@jchate6 Do you mean that those units should not be required, i.e. you should be allowed to submit a brightness without a brightness unit? Or should it still be required but only if a brightness has been filled in? I agree in principle that they should not be filled in by default, just trying to hash out the specifics before I change it.

[jchate6]

@jnation3406 Thanks for checking. The second option was what I was thinking. They should definitely be required if a corresponding value is present, but be blank until a user makes a selection.