feat(Dockerfile): install git toolchain in `bitnami/kubectl` (#43)

kubectl binary also include kustomize to build configurable manifest. kubectl kustomize supports three options: "no flag", "directory" and "url".

The official documentation show the following example:

kubectl kustomize "https://github.com/kubernetes-sigs/kustomize.git/exam
ples/helloWorld?ref=v1.0.6"

But it does not work with bitnami/kubectl:latest

docker run --rm bitnami/kubectl:latest kustomize "https://github.com/
kubernetes-sigs/kustomize.git/examples/helloWorld?ref=v1.0.6"
error: no 'git' program on path: exec: "git": executable file not found
in $PATH

The problem is that it requires git to pull the repository and execute it. This commit include git-all in the installed package to solve this issue.

Signed-off-by: Vasek - Tom C tom.chauveau@epitech.eu