You can add an environment variable of your choosing to your local server, as well as your staging and production server, and check its value to use the appropriate ruby version, like this:
## based on an ENV variable
if ENV['KIND_OF_SERVER'] == "development"
ruby '2.0.0', patch_level: 353
else
ruby '1.9.3', engine: 'jruby', engine_version: '1.7.1'
end