This moves the various projects from "type-based" folders (such as
"services" or "tools") into more appropriate semantic folders (such as
"nix", "ops" or "web").
Deprecated projects (nixcon-demo & gotest) which only existed for
testing/demonstration purposes have been removed.
(Note: *all* builds are broken with this commit)
Newer versions of nginx apparently hard-crash if they can't write a
PID file in the current directory.
To work around this, some writeable scratch space is created for the
nginx daemon to write its PID to.
