Refactor Mootiro Importer

 - Print some info using logger
 - Extract `build_*` functions from all `import_*` functions (to facilitate the tests)
 - Use `ST_FlipCoordinates` from PostGIS to fix the geometries
 - Save geometries using `update_columns` to avoid the creation of RGeo objects
 - Create a function to extract geometries from geometry collections (not been used)
 - Add some specs