update readme and a few other tweaks
diff --git a/voltha b/voltha
index 7aa1054..79862f0 100755
--- a/voltha
+++ b/voltha
@@ -78,7 +78,7 @@
 WITH_ONOS=${WITH_ONOS:-yes}
 WITH_CHAOS=${WITH_CHAOS:-no}
 WITH_ADAPTERS=${WITH_ADAPTERS:-yes}
-WITH_SIM_ADAPTERS=${WITH_SIM_ADAPTERS:-yes}
+WITH_SIM_ADAPTERS=${WITH_SIM_ADAPTERS:-no}
 WITH_OPEN_ADAPTERS=${WITH_OPEN_ADAPTERS:-yes}
 WITH_PORT_FORWARDS=${WITH_PORT_FORWARDS:-yes}
 ONLY_ONE=${ONLY_ONE:-yes}
@@ -101,6 +101,7 @@
 VOLTHA_ADAPTER_OPEN_OLT_CHART_VERSION=${VOLTHA_ADAPTER_OPEN_OLT_CHART_VERSION:-latest}
 VOLTHA_ADAPTER_OPEN_ONU_CHART=${VOLTHA_ADAPTER_OPEN_ONU_CHART:-onf/voltha-adapter-openonu}
 VOLTHA_ADAPTER_OPEN_ONU_CHART_VERSION=${VOLTHA_ADAPTER_OPEN_ONU_CHART_VERSION:-latest}
+ONOS_CHART=${ONOS_CHART:-onf/onos}
 ONOS_CHART_VERSION=${ONOS_CHART_VERSION:-latest}
 EXTRA_HELM_INSTALL_ARGS=
 NUM_OF_BBSIM=${NUM_OF_BBSIM:-1}
@@ -196,6 +197,7 @@
     VOLTHA_ADAPTER_OPEN_OLT_CHART_VERSION \
     VOLTHA_ADAPTER_OPEN_ONU_CHART \
     VOLTHA_ADAPTER_OPEN_ONU_CHART_VERSION \
+    ONOS_CHART \
     ONOS_CHART_VERSION \
     ONOS_API_PORT \
     ONOS_SSH_PORT \
@@ -216,6 +218,23 @@
     fi
 done
 
+# Check for prerequiste tools
+TOOLS="go curl sed jq"
+if [ $DEPLOY_K8S == "yes" ]; then
+    TOOLS+=" docker"
+fi
+NOT_FOUND=""
+for T in $TOOLS; do
+    if [ -z "$(which $T)" ]; then
+        NOT_FOUND+=" $T"
+    fi
+done
+
+if [ ! -z "$NOT_FOUND" ]; then
+    >&2 echo -e "${RED}${BOLD}${ERROR}ERROR:${NORMAL}${RED} The following required tools where not found, please install them:$NOT_FOUND"
+    exit 1
+fi
+
 mkdir -p .voltha
 touch .voltha/ports
 HAVE=$(grep $NAME .voltha/ports)
@@ -1119,7 +1138,7 @@
     bspin "Verify ONOS installed $BIRD"
     if [ $(helm list --deployed --short --namespace default "^onos\$" | wc -l) -ne 1 ]; then
         espin $NOT_VERIFIED
-        EXTRA_HELM_FLAGS="$SET_TAG $EXTRA_HELM_FLAGS" helm_install - default onos onf/onos $ONOS_CHART_VERSION "Install ONOS"
+        EXTRA_HELM_FLAGS="$SET_TAG $EXTRA_HELM_FLAGS" helm_install - default onos $ONOS_CHART $ONOS_CHART_VERSION "Install ONOS"
     else
         espin $VERIFIED
     fi