Add multiple Dockerfile templates, not just HTTPd

Description

Creating Dockerfiles is difficult. We can make it easier by providing templates. We currently have one template, for HTTPd. We should create more.

Proposal

• Create Dockerfile templates for Ruby, Rails, Node.js, PHP, Python, Java.

Links

• This is a todo on the page: https://about.gitlab.com/handbook/sales/idea-to-production-demo