set parameterCd default to 'None'

[mroberge]

If you specify a parameterCd in your request, the NWIS will return data only for that parameter. Instead, make the default be parameterCd = None, so that the default request will return all of the parameters collected at the site.

If I set parameterCd=None, will the request add parameterCd to the url, or does it drop parameters that are set to None?

[* edit mcr 2/11/19] ==> This works. If you don't specify a parameterCd now, NWIS will return every parameter.

[mroberge]

Alternatively, it might be nice to make the default be: parameterCd = 'all' just so that it is obvious that everything will be returned.

[mroberge]

Before closing this issue, the 'all' idea should be implemented:

• set the default for parameterCd to 'all'
• during NWIS.init() store 'all' in the parameterCd property.
• during hf.get_nwis(), convert 'all' to None before constructing the URL.
• when data gets returned, list all of the parameterCodes that get returned in the parameterCd property.
  • This will have to wait for a later change.

[mroberge]

closed with 39b347c.