Updating to onos:2.2.6-rc1 and using released version of olt and dhcpl2relay apps. Releases voltha-onos:4.1.7

Change-Id: I3ee215bdc123693fbe0fbe957a9b7e4270d05a34
diff --git a/VERSION b/VERSION
index 0211f69..9edf2a4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.1.6-dev
+4.1.7