Add a trifle of i18n to KeyVerificationView

Two strings were left behind:
- "Their identity (they read)"
- "Your identity (you read)"

I saved them.

// FREEBIE

_locales/en/messages.json

@@ -97,6 +97,13 @@
     "verifyIdentity": {
         "message": "Verify Identity"
     },
+    "theirIdentity": {
+        "message": "Their identity (they read):",
+        "description": "They is used here as a gender-neutral third-person singular"
+    },
+    "yourIdentity": {
+        "message": "Your identity (you read):"
+    },
     "deleteMessages": {
         "message": "Delete messages"
     },

background.html

@@ -216,11 +216,11 @@
         <span class='conversation-title'>{{ verifyIdentity }}</span>
     </div>
     <div class='container'>
-      <p> Their identity (they read): </p>
+      <p> {{theirIdentity}} </p>
       <div class='key'>
         {{ #their_key }} <span>{{ . }}</span> {{ /their_key }}
       </div>
-      <p> Your identity (you read): </p>
+      <p> {{yourIdentity}} </p>
       <div class='key'>
         {{ #your_key  }} <span>{{ . }}</span> {{ /your_key  }}
       </div>

js/views/key_verification_view.js

@@ -27,6 +27,8 @@
         render_attributes: function() {
             return {
                 verifyIdentity: i18n('verifyIdentity'),
+                yourIdentity: i18n('yourIdentity'),
+                theirIdentity: i18n('theirIdentity'),
                 your_key: this.splitKey(this.model.your_key),
                 their_key: this.splitKey(this.model.their_key)
             };