Add new parameter to Twitch usher URL
Add new parameter to Twitch usher URL

Livestreamer was getting a "Player must be spectre-aware" error when it
tried to get the list of available HLS streams from some Twitch channels
(those playing a playlist?). To avoid this error, the usher service URL
now requires a new parameter called "allow_spectre" to be defined. Since
I don't know how this "spectre" thing works, I set the parameter to
"false".

chrippa/livestreamer,intact/livestreamer,intact/livestreamer,chhe/livestreamer,Dobatymo/livestreamer,chrippa/livestreamer,Dobatymo/livestreamer,chhe/livestreamer