* Update the Travis and CircleCI Go versions
* Adapt to new gofmt formatting
The formatting of gofmt changed slightly in go 1.11. The release
notes recommend to use a specific binary of gofmt. See
https://golang.org/doc/go1.11#gofmt
This commit adapts to the new formatting applied by gofmt and changes
the configs for travis and circleci to run gofmt only with go 1.11.
Michael