Translate 'email' threepid label

src/components/structures/UserSettings.js

@@ -826,6 +826,7 @@ module.exports = React.createClass({
 
     nameForMedium: function(medium) {
         if (medium === 'msisdn') return _t('Phone');
+        if (medium === 'email') return _t('Email');
         return medium[0].toUpperCase() + medium.slice(1);
     },
 

src/i18n/strings/en_EN.json

@@ -227,6 +227,7 @@
   "Drop here %(toAction)s": "Drop here %(toAction)s",
   "Drop here to tag %(section)s": "Drop here to tag %(section)s",
   "Ed25519 fingerprint": "Ed25519 fingerprint",
+  "Email": "Email",
   "Email Address": "Email Address",
   "Email, name or matrix ID": "Email, name or matrix ID",
   "Emoji": "Emoji",