one less hard coded reference

 * Bosh::Dev::Build uses Pipeline#base_url to find s3 bucket
Show step message before long-running block result

[finishes #53005303]

This means #step can be used to display what is currently
happening whilst determining OK/FAILED.
clean up style and syntax
Update debugger-ruby_core_source to install with 1.9.3-p448
Refactored deployment test and removed stubbed methods on object under test
Made CLI error output go to stderr instead of stdout.

Refactored runner spec.

[#52679555]

Signed-off-by: Matthew Boedicker <mboedicker@pivotallabs.com>