Releasing voltha-onos with updated apps and ONOS 2.2.8 for VOLTHA 2.7

Change-Id: Ic3291db86fee2ae8deec37d48db0b2737fc74f9c
diff --git a/Dockerfile.voltha-onos b/Dockerfile.voltha-onos
index a7359f7..a234219 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-latest as install
+FROM onosproject/onos:2.2.8 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-latest
+FROM onosproject/onos:2.2.8
 
 # The ENV settings must be replicated below as they are not shared between stages
 ENV ONOS=/root/onos