Add remaining translations!

Every file has now been manually vetted by me. Due to the extent of
the changes, I've been unable to test all scenarios to make sure this
all works. :(

src/components/views/rooms/ReadReceiptMarker.js

@@ -23,6 +23,7 @@ var sdk = require('../../../index');
 
 var Velociraptor = require('../../../Velociraptor');
 require('../../../VelocityBounce');
+import { _t } from '../../../languageHandler';
 
 import DateUtils from '../../../DateUtils';
 
@@ -169,8 +170,10 @@ module.exports = React.createClass({
 
         let title;
         if (this.props.timestamp) {
-            title = "Seen by " + this.props.member.userId + " at " + 
-                    DateUtils.formatDate(new Date(this.props.timestamp));
+            title = _t(
+                "Seen by %(userName)s at %(dateTime)s",
+                {userName: this.props.member.userId, dateTime: DateUtils.formatDate(new Date(this.props.timestamp))}
+            );
         }
 
         return (