[RELEASE] Released version 2.3-dev0

Released version 2.3-dev0 with the following main changes :
    - exact copy of 2.2.0
diff --git a/VERSION b/VERSION
index ccbccc3..a9ef356 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.2.0
+2.3-dev0