streamlink: update to 0.8.1

0.8.1:
        Multiple plugin fixes (twitch, vaughlive, hitbox, etc.)
        Donations! We've gone ahead and joined the Open Collective at https://opencollective.com/streamlink
        Multiple doc updates
        Support for SOCKS proxies
        Code refactoring

0.7.0:
        Stream types will now be sorted accordingly in terms of quality
        TeamLiquid.net Plugin added
        Numerous plugin & bug fixes
        Updated HomeBrew package
        Improved CLI documentation

0.6.0:
We've updated more plugins, improved documentation, and moved out nightly builds to Bintray (S3 was costing wayyyy too much).

Full changelog at:
https://streamlink.github.io/changelog.html

(maya)