updates deps, add vendor directory and make build-with-vendor

[chrroberts-pure]

closes #120

• adds the following Makefile features

make build-with-vendor make update-go-deps

• adds the vendor directory for easier transport to easier compiling at customers sites.

tested with builds with and without the vendor directory, and with the dockerfile.

[james-laing]

Thanks for this @chrroberts-pure. This will be most helpful for a customer requiring this feature. I have tested and working ok.