waterdata module - option to remove "superfluous" ID columns and move stable ID columns to end of the dataframe

[ehinman]

Every dataframe returned has an "id" column that the waterdata module renames to the appropriate [service]_id. Some ids are ephemeral in the database and are meaningless to the user; they cannot be relied upon to pull the same result through time. These include:
"daily_id" from the daily service
"latest_continuous_id" from the latest continuous service
"latest_daily_id" from the latest daily service
"continuous_id" from the continuous service
"field_measurement_id" from the field measurements service

However, some ids are inherently meaningful. These include:
"monitoring_location_id"
"field_visit_id"
"time_series_id"

This issue covers adding an argument arbitrarily set to "True" that removes those superfluous id columns in the first list.

[ehinman]

Addressed partially by #203, but did not remove superfluous columns completely, just moved them to the end.