Fix key conflict dialog i18n

Allow html in this i18n message. TODO: re-design this dialog.

Fixes #584

// FREEBIE

background.html

@@ -290,7 +290,7 @@
   <script type='text/x-tmpl-mustache' id='key-conflict-dialogue'>
     <div class='content'>
       <p> {{ message }} </p>
-      <p> {{ verifyContact }} </p>
+      <p> {{{ verifyContact }}} </p>
       <p>
         <button class='cancel'>{{ cancel }}</button>
         <button class='resolve'>{{ resolve }}</button>