UX: remove "at" word from relative dates in local dates

Previously we would render "Today at 2:42 PM"
Now we render "Today 2:42 PM"

This also introduces new strings so it can be properly translated

Finally it introduces tests so we can make sure this keeps working

plugins/discourse-local-dates/assets/javascripts/discourse-local-dates.js

@@ -56,6 +56,26 @@
       var displayTimezone = moment.tz.guess();
       var relativeTime = relativeTime.tz(displayTimezone);
 
+      var d = function(key) {
+        var translated = I18n.t("discourse_local_dates.relative_dates." + key, {
+          time: "LT"
+        });
+        translated = translated
+          .split("LT")
+          .map(function(w) {
+            return "[" + w + "]";
+          })
+          .join("LT");
+        return translated;
+      };
+
+      var relativeFormat = {
+        sameDay: d("today"),
+        nextDay: d("tomorrow"),
+        lastDay: d("yesterday"),
+        sameElse: "L"
+      };
+
       if (
         options.format !== "YYYY-MM-DD HH:mm:ss" &&
         relativeTime.isBetween(
@@ -63,7 +83,7 @@
           moment().add(2, "day")
         )
       ) {
-        relativeTime = relativeTime.calendar();
+        relativeTime = relativeTime.calendar(null, relativeFormat);
       } else {
         relativeTime = relativeTime.format(options.format);
       }

plugins/discourse-local-dates/config/locales/client.en.yml

@@ -1,6 +1,10 @@
 en:
   js:
     discourse_local_dates:
+      relative_dates:
+        today: Today %{time}
+        tomorrow: Tomorrow %{time}
+        yesterday: Yesterday %{time}
       title: Insert date
       create:
         modal_title: Insert date

plugins/discourse-local-dates/test/javascripts/acceptance/local-dates-test.js.es6

@@ -6,9 +6,36 @@ acceptance("Local Dates", {
   settings: { discourse_local_dates_enabled: true },
   beforeEach() {
     clearPopupMenuOptionsCallback();
+  },
+  afterEach() {
+    sinon.restore();
   }
 });
 
+test("at removal", assert => {
+  let now = moment("2018-06-20").valueOf();
+  let timezone = moment.tz.guess();
+
+  sinon.useFakeTimers(now);
+
+  let html = `<span data-timezones="${timezone}" data-timezone="${timezone}" class="discourse-local-date past cooked-date" data-date="DATE" data-format="L LTS" data-time="14:42:26"></span>`;
+
+  let yesterday = $(html.replace("DATE", "2018-06-19"));
+  yesterday.applyLocalDates();
+
+  assert.equal(yesterday.text(), "Yesterday 2:42 PM");
+
+  let today = $(html.replace("DATE", "2018-06-20"));
+  today.applyLocalDates();
+
+  assert.equal(today.text(), "Today 2:42 PM");
+
+  let tomorrow = $(html.replace("DATE", "2018-06-21"));
+  tomorrow.applyLocalDates();
+
+  assert.equal(tomorrow.text(), "Tomorrow 2:42 PM");
+});
+
 test("local dates bbcode", async assert => {
   await visit("/");
   await click("#create-topic");