For security reasons, CircleCI does not make environment variables
available on forked repositories (often used in PRs). This will still
build the docker image, but won't try to push it to dockerhub.
* Port toml-test to pure Go
This change basically ports the toml-test examples test suite to pure
Go. This removes the snowflake test.sh required to run such tests, and
allows us to the example tests on any platform (which includes Windows
as part of the pull-request testing).
* Allow CircleCI failure for go tip
Thomas Pelletier