watershed outlet-finding script has extra boolean

[corviday]

When you run the watershed outlet-finding script, you get this error:

Traceback (most recent call last):
  File "mouths-of-watersheds.py", line 67, in <module>
    if not cell_routing.mask and not flag:
NameError: name 'flag' is not defined

Removing and flag seems to fix it.

[rod-glover]

That does leave the question hanging there: "What is/was flag supposed to be?"

[corviday]

This script also labels a column WTRSHDGRPC (alphanumberic index) but outputs WTRSHDGRPD (numerical index) into that column. A minor quibble; either one uniquely identifies a watershed, but slightly confusing.

[corviday]

Other changes that would be nice for increased flexibility, as this script is applied to more data going forward:

• Accept a shapefile as input, instead of a geoserver response; geoserver will probably not be part of this toolchain much longer
• Accept an argument indicating which attribute to output as the identifying attribute in the output CSV. Currently it is hardcoded to output WTRSHDGRPD, not all shapefiles have one of those.