This

- better illustrates what components do (provide building recipes for
  programs) and what software do (gather components and provide recipes
  for instances).

- illustrates how to build the software properly - usually we build
  eggs or scripts with zc.recipe.egg:* , not generate python programs via
  jinja2 templating. Because when installing via egg, it is possible to
  import other installed eggs relatively straghtforward, and for jinja2
  way it is hard to do.

The helloweb program itself is moved into newly introduced helloweb.git
repository and, as almost all other software, becomes separate from
slapos.git .

/cc @jerome