Use a single-stage build for now since Docker Hub doesn't support multi-stage builds. Also updated base image to current version of Go, 1.8

Use the same format output for warnings even if they aren’t related to
a specific test ID

Updates to travis file, readme and help text

The Github project name was changed to "kube-bench" so there was a need to modify
Dockerfile references.
Also modified the text output of the entrypoint to be friendlier.

Simply clone the project, compile the go app and run ./cis_kubernetes

* Replace the default help text

* Readme file, including the test config format documentation

* Typo

* Warn if config files / executables aren't found

* Ignore original name of executable (as per current README)

* Update tests to avoid failing on stat of a non-existant file

* Add a makefile for ease of build