Add GCE-related libs to make-env-slave.sh virtualenv
Add GCE-related libs to make-env-slave.sh virtualenv

umbrant/dist_test,cloudera/dist_test,xiao-chen/dist_test,cloudera/dist_test,xiao-chen/dist_test,xiao-chen/dist_test,umbrant/dist_test,umbrant/dist_test,cloudera/dist_test,cloudera/dist_test,umbrant/dist_test,xiao-chen/dist_test