Moving VOLTHA-ONOS to depend on onos:2.2.6 and releasing 4.1.8

Change-Id: I3f0697eb9353d07eaded74f1f26334566296bdfa
diff --git a/Dockerfile.voltha-onos b/Dockerfile.voltha-onos
index 8a37a79..c00173f 100644
--- a/Dockerfile.voltha-onos
+++ b/Dockerfile.voltha-onos
@@ -34,7 +34,7 @@
 
 
 # Unpack and install specific apps from download stage
-FROM onosproject/onos:2.2.6-rc1 as install
+FROM onosproject/onos:2.2.6 as install
 
 # The ENV settings must be replicated below as they are not shared between stages
 ENV ONOS=/root/onos
@@ -58,7 +58,7 @@
 
 
 # Create the final image coping over the installed applications from the install stage
-FROM onosproject/onos:2.2.6-rc1
+FROM onosproject/onos:2.2.6
 
 # The ENV settings must be replicated below as they are not shared between stages
 ENV ONOS=/root/onos
diff --git a/VERSION b/VERSION
index 9edf2a4..a7c00da 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.1.7
+4.1.8