Get off off rails-assets

Just moving the things we currently use (and should drop in the ASAP) to vendor/assets

vendor/assets/javascripts/momentjs/src/lib/utils/abs-round.js

@@ -0,0 +1,7 @@
+export default function absRound(number) {
+    if (number < 0) {
+        return Math.round(-1 * number) * -1;
+    } else {
+        return Math.round(number);
+    }
+}