Simple helloweb in Go that does the same as Python and Ruby versions.

/cc @gabriel, @Camata

Let's show how to do simple helloweb in Ruby. The program generates the
same output as Python version, only the comment about language is
different.

Comes with minimal gem specification, so it could be worked with /
installed via Bundler, together with dependency gems, if needed.

So far we use only stdlib without external gems.

/cc @kazuhiko

We'll soon have several helloweb programs written in different languages
with otherwise the same output, and it is better to distinguish them for
diagnostic.

So that it can be installed as egg/scripts via std setuptools machinery.

This is my simple program originally from slapos.git repository:

    nexedi/slapos@7cd2f953

with all follow-up changes to it in slapos.git tree.

A simple project showing how to say hello to the Web in different ways.