Draft out a description of upstart

This is a short description of how upstart works. I provide an
example of starting an httpd.
This description is not intended as a replace of upstart's documentation

Missing: links to that documentation would be grand..
Typos, corrections and rewording

rebase against master.

rewrite intro, to be less awkward and actually fully cover upstart's
functionality.
file-system -> filesystem. Remove commas in places where they don't
belong, and add them to places where they do belong instead.
Explain show-config output.
Merge pull request #115 from igalic/init_upstart

Init upstart