Fix USA's state geojson for 'Country Map' visualization (#4121)

* Fix USA's state geojson for 'Country Map' visualization

Turns out the ISO codes were missing from the geojson file, this adds it
and uses human-readable indents.

* using proper ISO codes

* Linting

New linting rules started applying, I'm guessing a new version of
pylint?

superset/sql_lab.py

@@ -240,7 +240,7 @@ def execute_sql(
                 limit=query.limit,
                 schema=database.force_ctas_schema,
                 show_cols=False,
-                latest_partition=False, ))
+                latest_partition=False))
     query.end_time = utils.now_as_float()
     session.merge(query)
     session.flush()