Modify jquery.timeago to better support i18n

Use string interpolation instead of concatenation of prefix, content,
and suffix. This is motivated by the fact that Transifex does not accept
empty strings for translation (even when pgettext is used to provide
context).

common/static/js/src/jquery.timeago.locale.js

 jQuery.timeago.settings.strings = {
-    prefixAgo: pgettext("Prefix indicating time ago", ""),
-    prefixFromNow: pgettext("Prefix indicating time from now", ""),
-    suffixAgo: pgettext("Suffix indicating time ago", "ago"),
-    suffixFromNow: pgettext("Suffix indicating time from now", "from now"),
+    formatAgo: gettext("%s ago"),
+    formatFromNow: gettext("%s from now"),
     seconds: gettext("less than a minute"),
     minute: gettext("about a minute"),
     minutes: function(value) { return ngettext("%d minute", "%d minutes", value)},
@@ -14,6 +12,5 @@ jQuery.timeago.settings.strings = {
     months: function(value) { return ngettext("%d month", "%d months", value) },
     year: gettext("about a year"),
     years: function(value) { return ngettext("%d year", "%d years", value) },
-    wordSeparator: pgettext("Word separator", " "),
     numbers: []
 };

common/static/js/vendor/jquery.timeago.js

@@ -6,12 +6,12 @@
  * @version 0.11.4
  * @requires jQuery v1.2.3+
  * @author Ryan McGeary
- * @license MIT License - http://www.opensource.org/licenses/mit-license.php
  *
  * For usage and examples, visit:
  * http://timeago.yarp.com/
  *
- * Copyright (c) 2008-2012, Ryan McGeary (ryan -[at]- mcgeary [*dot*] org)
+ * Portions copyright (c) 2008-2012, Ryan McGeary (ryan -[at]- mcgeary [*dot*] org)
+ * and licensed under the MIT license (http://www.opensource.org/licenses/mit-license.php)
  */
 (function($) {
   $.timeago = function(timestamp) {
@@ -32,10 +32,8 @@
       refreshMillis: 60000,
       allowFuture: false,
       strings: {
-        prefixAgo: null,
-        prefixFromNow: null,
-        suffixAgo: "ago",
-        suffixFromNow: "from now",
+        formatAgo: "%s ago",
+        formatFromNow: "%s from now",
         seconds: "less than a minute",
         minute: "about a minute",
         minutes: "%d minutes",
@@ -47,18 +45,15 @@
         months: "%d months",
         year: "about a year",
         years: "%d years",
-        wordSeparator: " ",
         numbers: []
       }
     },
     inWords: function(distanceMillis) {
       var $l = this.settings.strings;
-      var prefix = $l.prefixAgo;
-      var suffix = $l.suffixAgo;
+      var format = $l.formatAgo;
       if (this.settings.allowFuture) {
         if (distanceMillis < 0) {
-          prefix = $l.prefixFromNow;
-          suffix = $l.suffixFromNow;
+          format = $l.formatFromNow;
         }
       }
 
@@ -86,8 +81,7 @@
         years < 1.5 && substitute($l.year, 1) ||
         substitute($l.years, Math.round(years));
 
-      var separator = $l.wordSeparator === undefined ?  " " : $l.wordSeparator;
-      return $.trim([prefix, words, suffix].join(separator));
+      return $.trim(format.replace(/%s/i, words));
     },
     parse: function(iso8601) {
       var s = $.trim(iso8601);