Create docker build images

[renecannao]

Why

The current way of making packages is extremely slow (and requires network connectivity) .

What

We need to provide base images where proxysql can be compiled
Base images for:

• Centos7
• Ubuntu 12
• Ubuntu 14

[renecannao]

I created a git repo for creating images:
https://github.com/renecannao/docker-images

Images will be available at:
https://hub.docker.com/r/renecannao/proxysql/

[renecannao]

Pushed 3 images with 3 different tags

[renecannao]

pushed also image proxysql:dev