Improve client.py log messages in Jenkins environments
Improve client.py log messages in Jenkins environments

* Avoid printing color codes
* Do not print unless the result has changed
* Print a success/fail message at the end too, colorized

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