Fix #2402 - Add Idempotency-Key header to PostStatusService that prevents (#2419)

duplicates. Web UI regenerates UUID for that header every time the compose
form is changed or successfully submitted

Also, fix Farsi i18n overwriting the English one

app/assets/javascripts/components/uuid.jsx

@@ -0,0 +1,3 @@
+export default function uuid(a) {
+  return a ? (a^Math.random() * 16 >> a / 4).toString(16) : ([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g, uuid);
+};