st2bootstrap generic template

[nzlosh]

This PR rewrites the st2bootstrap script generation process to use jinja templates. A datafile is used to define the set of supported Linux distributions. Jinja templates are defined by functionality, e.g. a mongodb template, redis template, systems template etc to give modularity to the shell script.

Documentation describing how the template and scripts are structured in readme-install-script.md

The re-write is fundamental to addressing package build / test and publish failures in the st2 ci/cd. It has been failing for the last year due to lack of maintenance to the st2bootstrap script.

[cognifloyd]

I finally finished reviewing this. I've got some questions and suggested changes.

[cognifloyd]

This is so close! And it is so much easier to follow the logic of these templates, minimizing the duplication from the old method.

[cognifloyd]

Woohoo. The only question left is about that packaging bug and you mentioned adding a comment about the ASCII logo. In any case I'm satisfied. This looks great!

[cognifloyd]

Shame on node.js! Oh well.

[nzlosh]

@cognifloyd If you're OK with circling back to the packaging /var/log/st2 issue later on, I think I've addressed all other points.

[cognifloyd]

@cognifloyd If you're OK with circling back to the packaging /var/log/st2 issue later on, I think I've addressed all other points.

Yup. Sounds good. Merge!