ida-story [3]launcher now can continue on error

compute launcher now accepts option --continue_on_error.
if the option is not provided it will stop on first runtime exception by
default.
I have also pulled exceotion handling to top layer(launch) as part of
this PR.
got rid of unnecessary instance variable
fixed indentation in vapp_orchestrator
removed not so useful test

this behavior is now being tested in launch_spec.rb
making launcher logging better

- added spacing between log msges for vapps.making them more readable
- added logging after a vapp is succefully provisioned. this was missing
fixing cucumber
Merge pull request #98 from alphagov/continue_on_error_option

Continue on error option