Add support for running the cfnc in docker containers

[rbalman]

Summary
Right now to run the cfnc command either you need to install Golang and compile or install the compiled cfnc binary. Both of them might not be the right choice if you don't want to install and run it as a docker container.

In the scope of this story:

• let's dockerize the cfnc as a executable container
• publish it in the registry and update the CI
• finally update the documentation

eg. outcome: the help command should work as below

docker run cfnc --help

Manage cloudformation stacks at scale. Design and deploy multiple cloudformation stacks either in sequence or in prallel using declarative configuration

Usage:
  cfnc [command]

Available Commands:
  completion  Generate the autocompletion script for the specified shell
  config      Generate, validate and visualize the compose configuration
  deploy      Deploys the stacks based on the sequence specified in the compose configuration
  destroy     Destroys all the stacks in the reverse order of creation
  help        Help about any command

Flags:
  -c, --config string     File path to compose file (default "cfn-compose.yml")
  -d, --dry-run           Run commands in dry run mode
  -h, --help              help for cfnc
  -l, --loglevel string   Specify Log Levels. Valid Levels are: DEBUG, INFO, WARN, ERROR (default "INFO")
  -v, --version           version for cfnc

Use "cfnc [command] --help" for more information about a command.