Keyboard handlers, aria labels, locales cleanup

Added keyboard handlers for queue items
Fixed and/or added missing aria labels
Overlapping translations cleaned up + new ones added

src/locales/ja.json

@@ -18,8 +18,7 @@
         "feeds": "フィード",
         "offline": "オフライン",
         "logout": "ログアウト",
-        "restore_prefs": "設定用URLから復元",
-        "now_playing": "再生中"
+        "restore_prefs": "設定用URLから復元"
     },
     "action": {
         "back": "戻る",

src/locales/zh_Hans.json

@@ -27,8 +27,7 @@
         "feeds": "订阅源",
         "offline": "离线",
         "logout": "登出",
-        "restore_prefs": "还原偏好",
-        "now_playing": "正在播放"
+        "restore_prefs": "还原偏好"
     },
     "action": {
         "add": "添加",