Merge branch 'migration_es7' into 'development'

migration es7

See merge request !16

requirements.txt

@@ -7,7 +7,7 @@ pytz
 pymongo
 #tqdm
 # Elasticsearch 6.x
-elasticsearch>=6.0.0,<7.0.0
+elasticsearch>=7.0.0,<8.0.0
 # N.B.: GeoAlchemy2 0.6.1 does not accept POINTZ, MULTILINESTRINGZ, ... geometries
 GeoAlchemy2==0.5.0
 psycopg2-binary>=2.7.0