Add Jenkinsfile for integration tests matrix

Signed-off-by: Joffrey F <joffrey@docker.com>

Jenkinsfile

+#!groovy
+
+def imageNameBase = "dockerbuildbot/docker-py"
+def imageNamePy2
+def imageNamePy3
+def images = [:]
+def dockerVersions = ["1.12.3", "1.13.0-rc3"]
+
+def buildImage = { name, buildargs, pyTag ->
+  img = docker.image(name)
+  try {
+    img.pull()
+  } catch (Exception exc) {
+    img = docker.build(name, buildargs)
+    img.push()
+  }
+  images[pyTag] = img.id
+}
+
+def buildImages = { ->
+  wrappedNode(label: "ubuntu && !zfs && amd64", cleanWorkspace: true) {
+    stage("build image") {
+      checkout(scm)
+
+      imageNamePy2 = "${imageNameBase}:py2-${gitCommit()}"
+      imageNamePy3 = "${imageNameBase}:py3-${gitCommit()}"
+
+      buildImage(imageNamePy2, ".", "py2.7")
+      buildImage(imageNamePy3, "-f Dockerfile-py3 .", "py3.5")
+    }
+  }
+}
+
+def runTests = { Map settings ->
+  def dockerVersion = settings.get("dockerVersion", null)
+  def testImage = settings.get("testImage", null)
+
+  if (!testImage) {
+    throw new Exception("Need test image object, e.g.: `runTests(testImage: img)`")
+  }
+  if (!dockerVersion) {
+    throw new Exception("Need Docker version to test, e.g.: `runTests(dockerVersion: '1.12.3')`")
+  }
+
+  { ->
+    wrappedNode(label: "ubuntu && !zfs && amd64", cleanWorkspace: true) {
+      stage("test image=${testImage} / docker=${dockerVersion}") {
+        checkout(scm)
+        try {
+          sh """docker run -d --name dpy-dind-\$BUILD_NUMBER -v /tmp --privileged \\
+            dockerswarm/dind:${dockerVersion} docker daemon -H tcp://0.0.0.0:2375
+          """
+          sh """docker run \\
+            --name dpy-tests-\$BUILD_NUMBER --volumes-from dpy-dind-\$BUILD_NUMBER \\
+            -e 'DOCKER_HOST=tcp://docker:2375' \\
+            --link=dpy-dind-\$BUILD_NUMBER:docker \\
+            ${testImage} \\
+            py.test -rxs tests/integration
+          """
+        } finally {
+          sh """
+            docker stop dpy-tests-\$BUILD_NUMBER dpy-dind-\$BUILD_NUMBER
+            docker rm -vf dpy-tests-\$BUILD_NUMBER dpy-dind-\$BUILD_NUMBER
+          """
+        }
+      }
+    }
+  }
+}
+
+
+buildImages()
+
+def testMatrix = [failFast: false]
+
+for (imgKey in new ArrayList(images.keySet())) {
+  for (version in dockerVersions) {
+    testMatrix["${imgKey}_${version}"] = runTests([testImage: images[imgKey], dockerVersion: version])
+  }
+}
+
+parallel(testMatrix)