Alpine automated build

Merge branch 'dockerfile_alpine' of https://github.com/simongottschla…

…g/vouch-proxy into simongottschlag-dockerfile_alpine

Merge branch 'simongottschlag-adfs_get_username'

travis just test, docker just build

fix vouch#63 read only scope for github user info

vouch#62 vouch#61 make auth_url check provider aware

vouch#61 add oauth config to BasicTest

vouch#42 improve `vouch.domains` explanation

improve session key handling

Merge branch 'halkeye-fix-static'