Bump Golang 1.11.1
go1.11.1 (released 2018/10/01) includes fixes to the compiler,
documentation, go command, runtime, and the crypto/x509, encoding/json,
go/types, net, net/http, and reflect packages.
See the Go 1.11.1 milestone on our issue tracker for details:
https://github.com/golang/go/issues?q=milestone%3AGo1.11.1
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>