Localize strings in copypaste SOCKS sample

ran grunt test

There is a drop down that switches the language between Italian and English.
After migrating the popup to Polymer I can try a RTL language.
Let's make this part of `base`. Sooner or later some other piece of `third_party` code will appear here and I'd like to keep this as similar to `uproxy-lib` as possible to facilitate possible future merging of the repos.