Jenkins: configure for Gerrit

Change-Id: Idad10773f064c8e493cd12290925b6a4da958b9b

Jenkinsfile

 pipeline {
     agent any
-
+    triggers {
+        gerrit customUrl: '',
+            gerritProjects: [
+                [branches: [[compareType: 'PLAIN', pattern: 'master']],
+                 compareType: 'PLAIN',
+                 disableStrictForbiddenFileVerification: false,
+                 pattern: 'dhtnet']],
+            triggerOnEvents: [
+                commentAddedContains('!build'),
+                patchsetCreated(excludeDrafts: true, excludeNoCodeChange: true,
+                    excludeTrivialRebase: true)]
+    }
+    options {
+        ansiColor('xterm')
+    }
+    parameters {
+            string(name: 'GERRIT_REFSPEC',
+                   defaultValue: 'refs/heads/dhtnet',
+                   description: 'The Gerrit refspec to fetch.')
+    }
     stages {
+        stage('SCM Checkout') {
+            steps {
+                checkout changelog: true, poll: false,
+                    scm: [$class: 'GitSCM',
+                        branches: [[name: 'FETCH_HEAD']],
+                        doGenerateSubmoduleConfigurations: false,
+                        extensions: [
+                            [$class: 'CloneOption', noTags: true, reference: '', shallow: true],
+                            [$class: 'WipeWorkspace']],
+                        submoduleCfg: [],
+                        userRemoteConfigs: [[refspec: '${GERRIT_REFSPEC}', url: 'https://${JAMI_GERRIT_URL}/dhtnet']]]
+            }
+        }
         stage('Build') {
             steps {
                 script {