fix[closes #50]: Use apt-get instead of apt and fix go build

[lambdaclan]

Use apt-get instead of apt and fix go build

Closes #50

Related to: 60a7d88#r143184779

Description

1. apt is the recommended command for interactive use by administrators, not for use in shell scripts. Furthermore, the current use of apt is causing CLI warnings:

   >  apt does not have a stable CLI interface. Use with caution in scripts.
   

2. go build fails due to inconsistent package name

This PR updates the apt core package to use apt-get * command variants for all apt commands (install and clean) and fixes the incorrect package name so that the application can be successfully built.

Proposed Changes

• Use apt-get install instead of apt install
• Use apt-get clean instead of apt clean
• Update package name to match module directory (core)
• Some formatting changes (via https://github.com/incu6us/goimports-reviser)

Local Testing

Using the following vib.yml recipe:

name: my-recipe
id: my-test
stages:
  - id: build
    base: debian:sid-slim
    labels:
      maintainer: My Awesome Team
    args:
      DEBIAN_FRONTEND: noninteractive
    runs:
      - echo 'APT::Install-Recommends "0";' > /etc/apt/apt.conf.d/01norecommends
    modules:
      - name: update
        type: shell
        commands:
          - apt-get update
      - name: example-packages # Sample module using the built-in Apt module to install packages
        type: apt
        source:
          packages:
            - vim

vib build vim.yml

Generated Containerfile:

# Stage: build
FROM debian:sid-slim AS build
LABEL maintainer='My Awesome Team'
ARG DEBIAN_FRONTEND=noninteractive
RUN echo 'APT::Install-Recommends "0";' > /etc/apt/apt.conf.d/01norecommends
ADD includes.container /
ADD sources /sources
RUN apt-get update
RUN apt-get install -y  vim  && apt-get clean

[kbdharun]

LGTM, thanks for your contribution.

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Tested the changes locally, this PR is GTG.