VOL-2059 move ponsim-olt adapter to its own repo

Based on voltha-go commit 4f48884d490a3e6627687604ffdf885792326521

Change-Id: Idb23c4183888ed6bdc9ab24b109f505395e00821
diff --git a/VERSION b/VERSION
new file mode 100644
index 0000000..84e6d84
--- /dev/null
+++ b/VERSION
@@ -0,0 +1 @@
+2.2.1-dev