Tweak Aruba config for jRuby.

Tested with jruby-1.7.9, also add global @announce-cmd because it can
be tweaked to run quicker without cmd spawning a new Ruby process.
Merge pull request #153 from futhr/feature/tweak-aruba-jruby

Tweak Aruba config for jRuby.
Update deprecated File.exists?
Merge branch 'feature/change-file-exists' of github.com:futhr/localeapp into feature/change-file-exists