does stage_nwis_sitelist return too many sites?

going through tests in test-stage.R.

this used to return 22 sites (back in summer 2015) but now returns 1118.

``` r
stage_nwis_sitelist(c('doobs'), 'WI')
```

that would be ok if it were simply that WI has added a bunch of doobs sites. but the first three sites (and probably others) come back with nothing...

``` r
> staged <- stage_nwis_ts(sites[1:3], var="doobs", times=c('2006-01-01', '2016-04-05'), folder=folder)
> staged
NULL
```

also, a query by browser returns just 27 sites: http://waterdata.usgs.gov/nwis/uv?state_cd=wi&index_pmcode_00300=1&format=station_list&group_key=NONE&range_selection=days&period=7&begin_date=2007-01-01&end_date=2016-04-10&date_format=YYYY-MM-DD&rdb_compression=file&list_of_search_criteria=state_cd%2Crealtime_parameter_selection

this makes me suspect that `stage_nwis_sitelist` is not being sufficiently selective.