[Bug] random crash: 'NoneType' object has no attribute 'text'

This issue happens randomly with Windows; on different profiles. Doesn't happen at all with my linux install.

```
Loading pages |100%(87 of 87)|##################################################################################|Elapsed Time: 0:01:47 |ETA: 0:00:00
Traceback (most recent call last):

File "c:\python27\lib\runpy.py", line 162, in _run_module_as_main
"__main__", fname, loader, pkg_name)

File "c:\python27\lib\runpy.py", line 72, in _run_code
exec code in run_globals

File "C:\Python27\Scripts\instaLooter.exe\__main__.py", line 9, in

File "c:\python27\lib\site-packages\instaLooter\cli.py", line 130, in main
new_only=args['--new'],

File "c:\python27\lib\site-packages\instaLooter\core.py", line 388, in download
new_only=new_only)

File "c:\python27\lib\site-packages\instaLooter\core.py", line 451, in _fill_media_queue
medias_queued, stop = self._add_media_to_queue(media, condition, media_count, medias_queued, new_only)

File "c:\python27\lib\site-packages\instaLooter\core.py", line 462, in _add_media_to_queue
media_basename = self._make_filename(media)

File "c:\python27\lib\site-packages\instaLooter\core.py", line 503, in _make_filename
media = self.get_post_info(media['code'])

File "c:\python27\lib\site-packages\instaLooter\core.py", line 431, in get_post_info
media = self._get_shared_data(res)['entry_data']['PostPage'][0]['media']

File "c:\python27\lib\site-packages\instaLooter\core.py", line 445, in _get_shared_data
return json.loads(self._RX_SHARED_DATA.match(script.text).group(1))

AttributeError: 'NoneType' object has no attribute 'text'
```