/examples/hook/hook.go with it's child dependency on airbrake/gobrake is
not backwards compatible pre-go1.6 due to use of the following:
- os.LookupEnv (introduced in go1.5)
- http.StatusTooManyRequests (introduced in go1.6)
ignoring the fetch and explicit test of /examples/ fixes failing go1.3,
go1.4, go1.5 builds.
- Move to more recent version of Go, setting aside 1.1. - Use `install` instead of `before_script` to install library dependencies, as per [documentation](http://docs.travis-ci.com/user/languages/go/).