Set version to 2.13.14 and require Java 8

From Gerrit v2.13.14, Java 7 is not supported anymore
and the installer requires Java 8 as minimal version
to allow the setup of the Gerrit package.

Change-Id: Icb8a7f269bd7759ec84d1b7b04d6d014d61f761a
diff --git a/centos/7/Dockerfile b/centos/7/Dockerfile
index 5245a6f..372d80a 100644
--- a/centos/7/Dockerfile
+++ b/centos/7/Dockerfile
@@ -9,8 +9,8 @@
 
 # Install OpenJDK and Gerrit in two subsequent transactions
 # (pre-trans Gerrit script needs to have access to the Java command)
-RUN yum -y install java-1.7.0-openjdk
-RUN yum -y install gerrit-2.13.13
+RUN yum -y install java-1.8.0-openjdk
+RUN yum -y install gerrit-2.13.14
 
 USER gerrit
 RUN java -jar /var/gerrit/bin/gerrit.war init --batch --install-all-plugins -d /var/gerrit
diff --git a/ubuntu/14/Dockerfile b/ubuntu/14/Dockerfile
index 318847d..7078cef 100644
--- a/ubuntu/14/Dockerfile
+++ b/ubuntu/14/Dockerfile
@@ -12,8 +12,11 @@
 
 # Install OpenJDK and Gerrit in two subsequent transactions
 # (pre-trans Gerrit script needs to have access to the Java command)
-RUN apt-get -y install openjdk-7-jdk
-RUN apt-get -y install gerrit=2.13.13-1 && rm -f /var/gerrit/logs/*
+RUN apt-get -y install software-properties-common && \
+    add-apt-repository ppa:openjdk-r/ppa && \
+    apt-get update && \
+    apt-get -y install openjdk-8-jdk
+RUN apt-get -y install gerrit=2.13.14-1 && rm -f /var/gerrit/logs/*
 
 USER gerrit
 RUN java -jar /var/gerrit/bin/gerrit.war init --batch --install-all-plugins -d /var/gerrit