plugins.wattv: Minor tweaks and fixes.
plugins.wattv: Minor tweaks and fixes.

- Remove unnecessary headers.
- Fix Python 3 compatiblity.

sbstp/streamlink,okaywit/livestreamer,charmander/livestreamer,programming086/livestreamer,chhe/streamlink,wlerin/streamlink,Feverqwe/livestreamer,caorong/livestreamer,hmit/livestreamer,Feverqwe/livestreamer,flijloku/livestreamer,jtsymon/livestreamer,chhe/livestreamer,flijloku/livestreamer,programming086/livestreamer,beardypig/streamlink,hmit/livestreamer,lyhiving/livestreamer,Masaz-/livestreamer,bastimeyer/streamlink,Masaz-/livestreamer,gravyboat/streamlink,derrod/livestreamer,ethanhlc/streamlink,gravyboat/streamlink,mmetak/streamlink,bastimeyer/streamlink,intact/livestreamer,fishscene/streamlink,derrod/livestreamer,streamlink/streamlink,streamlink/streamlink,charmander/livestreamer,fishscene/streamlink,lyhiving/livestreamer,melmorabity/streamlink,melmorabity/streamlink,okaywit/livestreamer,intact/livestreamer,chhe/livestreamer,chrippa/livestreamer,jtsymon/livestreamer,chhe/streamlink,mmetak/streamlink,blxd/livestreamer,caorong/livestreamer,gtmanfred/livestreamer,Klaudit/livestreamer,back-to/streamlink,wlerin/streamlink,back-to/streamlink,javiercantero/streamlink,sbstp/streamlink,javiercantero/streamlink,Dobatymo/livestreamer,chrippa/livestreamer,wolftankk/livestreamer,blxd/livestreamer,gtmanfred/livestreamer,Klaudit/livestreamer,ethanhlc/streamlink,Saturn/livestreamer,wolftankk/livestreamer,beardypig/streamlink,Dobatymo/livestreamer,Saturn/livestreamer