Handle 'nan' type searches to avoid errors

[mcannon068nw]

Was doing a bulk search for a different project using dgipy.get_interactions and encountered a 'nan' in the dataset of type 'float'

This produced the error:

InvalidJSONError: Out of range float values are not JSON compliant

I think ideally a person using this search will have filtered out nan's or None's beforehand, but we should probably have something there to handle it just in case.

[jsstevenson]

We should double check that this is still possible, we've changed a lot of code since June 11th