* golint fixed for modules/setting

* typo fixed and renamed UNIXSOCKET to UnixSocket

* golint fixed for parts of routers root, dev and org dirs

* add user/auth.go golint fixed

* rename unnecessary exported to unexported and user dir golint fixed

- Update import paths from github.com/go-gitea to code.gitea.io
- Fix import path for travis

See https://docs.travis-ci.com/user/languages/go#Go-Import-Path

- #1496: fallback plain text
- #1002: add date header
- #913: fix encoding of header