Webapp: Route deletions cannot be done without removing entries from route_upstream

[saarasio]

Route id is a foreign key in route_upstream relationship table. Entry in this table should be deleted before the route is deleted.

When a route delete call is made, we could first delete the entries from route_upstream table.

9b1dd9:~ v3$ curl -s -X DELETE https://ingresspipe.io:8443/service/adminservice2/route/db_requests -H "Authorization: Bearer treehugger" | python -m json.tool
{
    "errors": [
        {
            "extensions": {
                "code": "constraint-violation",
                "path": "$"
            },
            "message": "Foreign key violation. update or delete on table \"route\" violates foreign key constraint \"route_upstream_route_id_fkey\" on table \"route_upstream\""
        }
    ]
}