RabbitMQ URL is now stored in 411 rabbitmq.conf file
node.xml: fix rabbitmq connection URL
commands: properly handle error cases and meaningfull error messages
use new format for rabbitmq.conf
mgstorage-pylib: catch exception thrown by popen

if something goes wrong with popen it fails with a stacktrace and no
errors to the client. With this patch it properly reports the problem
to the client
Merge branch 'master' into feature/sync_queue