detect failure of 'keystone token-get'

When 'keystone token-get' fails, the caller can't detect the failure.
This cause troulbe shooting a bit complicated.

Change-Id: I3c58c5fd0e92a87e87546ea797904e08646a1097
Closes-Bug: #1238412

exercises/neutron-adv-test.sh

@@ -102,6 +102,7 @@ KEYSTONE="keystone"
 # and save it.
 
 TOKEN=`keystone token-get | grep ' id ' | awk '{print $4}'`
+die_if_not_set $LINENO TOKEN "Keystone fail to get token"
 
 # Various functions
 # -----------------

stack.sh

@@ -1203,6 +1203,7 @@ fi
 
 if is_service_enabled g-reg; then
     TOKEN=$(keystone token-get | grep ' id ' | get_field 2)
+    die_if_not_set $LINENO TOKEN "Keystone fail to get token"
 
     if is_baremetal; then
        echo_summary "Creating and uploading baremetal images"

tools/upload_image.sh

@@ -33,6 +33,7 @@ fi
 
 # Get a token to authenticate to glance
 TOKEN=$(keystone token-get | grep ' id ' | get_field 2)
+die_if_not_set $LINENO TOKEN "Keystone fail to get token"
 
 # Glance connection info.  Note the port must be specified.
 GLANCE_HOSTPORT=${GLANCE_HOSTPORT:-$GLANCE_HOST:9292}