Docker images versioning in Jenkins pipeline

Properly tag generated Docker images.

Use a common [Jenkins shared library](https://gitlab.mim.ovh/EOLE/Zephir/jenkins).

Jenkinsfile

+// Import de la librairie Zéphir
+// Voir le projet https://gitlab.mim.ovh/EOLE/Zephir/jenkins
+@Library('zephir') _
+
+// Exécution du pipeline de construction des images
+serviceImagePipeline("zephir-saltmaster-manager")
\ No newline at end of file

ci/Dockerfile

+FROM docker:stable
+
+RUN apk add --no-cache git