Add warning message for qw data queries

[ehinman]

This MR adds warnings to nwis.get_qwdata and nwis.get_info when seriesCatalogOutput=True about the impending lack of updates to the qw service. Please review for accuracy in content and that the location and warning specifications are sufficient within the functions. Thanks!

[ehinman]

@thodson-usgs works for me. Changed.

[ehinman]

After chatting with @lstanish-usgs and @ldecicco-USGS, I think I have a few other messages to edit/add. This is still in draft. I will indicate when it's ready.

[ehinman]

@thodson-usgs, inspired by the approach taken by @ldecicco-USGS in R dataRetrieval, I'm wondering if nwis.get_info() should spit out warnings in multiple places: (1) A user could type in a 'parameterCd' and if I understand correctly, the sites service leverages the qw service to find sites with data for a given pcode. Is this correct? If so, I'd think we'd want to warn any users who use inputs that are water quality related. (2) A user might set seriesCatalogOutput to True, but the returned data may not contain any qw data. In this step, we could inspect the returned dataset for any data_type_cd == 'qw' and warn if present. What are your thoughts on this? Thanks!

[lstanish-usgs]

@ehinman thanks for the text update! Just one more date update for the nwis.py function, otherwise this looks good from my end. @thodson-usgs

[thodson-usgs]

Looks good to me

[ehinman]

Can you provide your input, @thodson-usgs? #134 (comment)

[thodson-usgs]

It's really the job of the service to provide these sorts of warnings, not the wrapping library (we merely convey them).
At least that's how things are supposed to work :).
In our case, I would create a warning function, as you did in wqp, so that you don't have to duplicate the message content.

[ehinman]

Sounds good @thodson-usgs. I am going to create a separate PR for it, so we can at least have some messaging out there right now.

[ehinman]

This MR is ready to merge on my end. @thodson-usgs @lstanish-usgs.

[lstanish-usgs]

@thodson-usgs this looks approved from my end, is it OK to go ahead and merge? Thanks