[Ximalaya] fix #1955
diff --git a/src/you_get/extractors/ximalaya.py b/src/you_get/extractors/ximalaya.py
index 58a158ba57..58e2945cb2 100644
--- a/src/you_get/extractors/ximalaya.py
+++ b/src/you_get/extractors/ximalaya.py
@@ -15,7 +15,8 @@
 
 def ximalaya_download_by_id(id, title = None, output_dir = '.', info_only = False, stream_id = None):
     BASE_URL = 'http://www.ximalaya.com/tracks/'
-    json_data = json.loads(get_content(BASE_URL + id + '.json'))
+    json_url = BASE_URL + id + '.json'
+    json_data = json.loads(get_content(json_url, headers=fake_headers))
     if 'res' in json_data:
         if json_data['res'] == False:
             raise ValueError('Server reported id %s is invalid' % id)

Now ximalaya api server checks UA. If there's 'python' (case insensitive) in UA it will return empty content instead of json string.

```
curl 'http://www.ximalaya.com/tracks/330957273.json' -H 'user-agent: python-urllib/3.5'
```
return nothing

```
curl 'http://www.ximalaya.com/tracks/3.json' -H 'user-agent: ython-urllib/3.5'
{"res":false}
```

```
./you-get -d 'http://www.ximalaya.com/2982325/sound/30957273'
[DEBUG] get_content: http://www.ximalaya.com/tracks/30957273.json
[DEBUG] ximalaya_download_by_id: http://audio.xmcdn.com/group24/M04/9E/A9/wKgJMFiq4_iDnkMKAZ_V_DLoKG4117.m4a
Site:        ximalaya.com
title:       01游玩天桥
Type:        MPEG-4 audio m4a
Size:        N/A
Downloading 01游玩天桥.m4a ...
 100% ( 26.0/ 26.0MB) ├█████████████████████████████████████████┤[1/1]    2 MB/s
```