[stable/jenkins] Update git plugin to 3.4.0 for CVE-2017-1000084 (#1505)

* [stable/jenkins] Update git plugin to 3.4.0 for CVE-2017-1000084

https://jenkins.io/security/advisory/2017-07-10/ has more information. 
Somewhat serious CSRF vulnerability.

* [stable/jenkins] Bump chart version

stable/jenkins/Chart.yaml

@@ -1,6 +1,6 @@
 name: jenkins
 home: https://jenkins.io/
-version: 0.8.1
+version: 0.8.2
 appVersion: 2.67
 description: Open source continuous integration server. It supports multiple SCM tools including CVS, Subversion and Git. It can execute Apache Ant and Apache Maven-based projects as well as arbitrary scripts.
 sources:

stable/jenkins/values.yaml

@@ -43,7 +43,7 @@ Master:
       - workflow-aggregator:2.5
       - workflow-job:2.13
       - credentials-binding:1.12
-      - git:3.3.1
+      - git:3.4.0
 # Used to approve a list of groovy functions in pipelines used the script-security plugin. Can be viewed under /scriptApproval
   # ScriptApproval:
   #   - "method groovy.json.JsonSlurperClassic parseText java.lang.String"