fix capistrano :use_sudo setting
fix capistrano :use_sudo setting

- explicit `set :use_sudo, true` in Capistrano should now trigger use of sudo
- anyone previously using :run_method should switch to :use_sudo
- :run_method is technically what Capistrano (and Sprinkle) use to decide
  how to run commands, but :run_method examines the :use_sudo setting to
  help make it's decision.  No need to mess with :run_method directly.
- Note: :use_sudo in Sprinkle::Capistrano defaults to false (unlike raw
  Capistrano, which defaults to true)

Resolves:
https://github.com/capistrano/capistrano/issues/211

sprinkle-tool/sprinkle,sprinkle-tool/sprinkle