Persian translation (#2405)

* Persian translation

* adding :fa to make the site use the rtl stylesheet

based on [this comment](https://github.com/tootsuite/mastodon/pull/2405#issuecomment-296721105)

* fix missing quotes

* add 'fa' locale

app/assets/javascripts/components/locales/index.jsx

@@ -2,6 +2,7 @@ import ar from './ar';
 import en from './en';
 import de from './de';
 import es from './es';
+import fa from './fa';
 import hr from './hr';
 import hu from './hu';
 import io from './io';
@@ -27,6 +28,7 @@ const locales = {
   en,
   de,
   es,
+  fa,
   hr,
   hu,
   io,