Improve error handling

- do not rescue Exception. This is the cause that sometimes CTRL+C was
not stopping the processes
(http://daniel.fone.net.nz/blog/2013/05/28/why-you-should-never-rescue-e
xception-in-ruby/
http://stackoverflow.com/questions/10048173/why-is-it-bad-style-to-rescu
e-exception-e-in-ruby etc…)
- rescue RuntimeError instead (probably still too wide, but the more
specific option that I was able to find)
- For unknown actions, add additional information (the actual name of
the action that was tried)
Verbose errors when failing to invoke a service