Adding a translation template

This will make it easier to translate to other languages.
Mentioning i18n in README

Should probably be documented on http://ivaynberg.github.com/select2/,
too, but I'm not very much of a Jekyll dude.
Suggesting author header in translation files

This can be highly useful when a translation need to be updated and you
need to contact an older translator.
Merge pull request #1026 from JensRantil/translation-process-improvements

Translation process improvements