Fix veehd isUniversal and properly handle when False is returned from get_host_and_id()

This is the fix for what I mentioned in skype. I changed init to set no valid resolvers in the case where a universal resolver is returned and the get_host_and_id call returns False. Let me know if that's not what you want to do and I'll change it. Without this change you get this:

```
15:22:18 T:2763176768   ERROR: EXCEPTION Thrown (PythonToCppException) : -->Python callback/script returned the following error<--
                                             - NOTE: IGNORING THIS CAN LEAD TO MEMORY LEAKS!
                                            Error Type: <type 'exceptions.TypeError'>
                                            Error Contents: 'bool' object is not iterable
                                            Traceback (most recent call last):
                                              File "/home/tknorris/.xbmc/addons/salts/default.py", line 1656, in <module>
                                                sys.exit(main())
                                              File "/home/tknorris/.xbmc/addons/salts/default.py", line 1649, in main
                                                url_dispatcher.dispatch(mode, _SALTS.queries)
                                              File "/home/tknorris/.xbmc/addons/salts/salts_lib/url_dispatcher.py", line 81, in dispatch
                                                self.func_registry[mode](*args, **kwargs)
                                              File "/home/tknorris/.xbmc/addons/salts/default.py", line 686, in get_sources
                                                hosters = filter_unusable_hosters(hosters)
                                              File "/home/tknorris/.xbmc/addons/salts/default.py", line 705, in filter_unusable_hosters
                                                hmf = urlresolver.HostedMediaFile(host=hoster['host'], media_id='dummy') # use dummy media_id to force host validation
                                              File "/home/tknorris/.xbmc/addons/script.module.urlresolver/lib/urlresolver/types.py", line 84, in __init__
                                                self._host, self._media_id = self._resolvers[0].get_host_and_id(self._url)
                                            TypeError: 'bool' object is not iterable
                                            -->End of Python script error report<--
15:22:18 T:3001972544   ERROR: Playlist Player: skipping unplayable item: 0, path [plugin://plugin.video.salts/?mode=get_sources&title=The+Lathe+of+Heaven&slug=the-lathe-of-heaven-1980&video_type=Movie&year=1980]
```