Check to see if GeoServer workspace exists before trying to delete it

[tnation14]

Problem description

The manage.py setup -G portion of scripts/load_configured_data fails on its first run in a clean environment because it tries to drop a GeoServer workspace that doesn't exist yet. purge_geoserver in config.py should only return False if the workspace exists and there was en error deleting it so that loading data into a new DistrictBuilder instance completes successfully.

[this should explain why the current behaviour is a problem and why the expected output is a better solution.]

Note: Please check first before submitting so that we do not have to handle and close duplicates!

Replication Steps

• Clone repo into a clean location
• run scripts/update
• Run scripts/load_configured_data

Expected Behavior or Output

scripts/load_configured_data completes successfully