added some dockers for building jenkins agents

docker-jenkins/build-initial-centos6.sh

@@ -0,0 +1,8 @@
+cd /tmp
+
+apt-get update &&
+yum install -y
+	openssh-server openssh-client openjdk-11-jdk openjdk-11-jre \
+	gcc gcc-c++ gcc-gnat gcc-java make autoconf automake libtool vim-enhanced &&
+useradd -m -s /bin/bash jenkins &&
+mkdir -p /var/run/sshd