[RELEASE] Released version 2.1-dev0

Released version 2.1-dev0 with the following main changes :
    - exact copy of 2.0.0
diff --git a/VERSION b/VERSION
index 227cea2..77a9f8e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.0.0
+2.1-dev0