Gwlevel url

Fixes #440 (closed) HOWEVER, will need to revisit when https://waterservices.usgs.gov/test-tools/?service=gwlevels&siteType=&statTypeCd=all&major-filters=sites&format=json&date-type=type-none&statReportType=daily&statYearType=calendar&missingData=off&siteStatus=all&siteNameMatchOperator=start is more mature (or is this it?)