Composable Default Recipe

This patch splits the default recipe out further into more composable pieces.

We'd like to use this cookbook in our infrastructure without modification, but we manage our services with `runit`. I've split the remaining parts of the default recipe up into sub-recipes (user, build, service) that can be included at-will by users who wish to deploy OpenResty in a different fashion that the default recipe specifies.

In the previous version, in order to install OpenResty one had to include the default recipe, which also installs OpenResty as a service with an init script at `/etc/init.d/nginx`. Now one can install OpenResty and any other features that this cookbook provides as separate pieces.

The behavior of the default recipe does not change.