Add geojson exporter

tests/test_exports.py

@@ -7,6 +7,7 @@ Code contributors: Pilar Monsalvete Alvarez de Uribarri pilar.monsalvete@concord
 """
 import json
 import logging.handlers
+import os
 from pathlib import Path
 from unittest import TestCase
 from hub.imports.geometry_factory import GeometryFactory
@@ -109,6 +110,7 @@ class TestExports(TestCase):
     self.assertEqual('Polygon', geometry['type'], 'Wrong geometry type')
     self.assertEqual(1, len(geometry['coordinates']), 'Wrong polygon structure')
     self.assertEqual(11, len(geometry['coordinates'][0]), 'Wrong number of vertices')
+    os.unlink(geojson_file)  # todo: this test need to cover a multipolygon example too
 
   def test_energy_ade_export(self):
     """