HADOOP-16054. Update Dockerfile to use Bionic.
HADOOP-16054. Update Dockerfile to use Bionic.


Contributed by Akira Ajisaka.
mapr/hadoop-common,wwjiang007/hadoop,nandakumar131/hadoop,mapr/hadoop-common,plusplusjiajia/hadoop,JingchengDu/hadoop,apurtell/hadoop,apurtell/hadoop,mapr/hadoop-common,JingchengDu/hadoop,nandakumar131/hadoop,mapr/hadoop-common,apache/hadoop,plusplusjiajia/hadoop,plusplusjiajia/hadoop,JingchengDu/hadoop,nandakumar131/hadoop,nandakumar131/hadoop,nandakumar131/hadoop,JingchengDu/hadoop,plusplusjiajia/hadoop,JingchengDu/hadoop,mapr/hadoop-common,steveloughran/hadoop,wwjiang007/hadoop,mapr/hadoop-common,wwjiang007/hadoop,apache/hadoop,JingchengDu/hadoop,apache/hadoop,apache/hadoop,apache/hadoop,apache/hadoop,mapr/hadoop-common,wwjiang007/hadoop,apache/hadoop,wwjiang007/hadoop,wwjiang007/hadoop,steveloughran/hadoop,plusplusjiajia/hadoop,nandakumar131/hadoop,steveloughran/hadoop,apurtell/hadoop,steveloughran/hadoop,apurtell/hadoop,steveloughran/hadoop,wwjiang007/hadoop,steveloughran/hadoop,apurtell/hadoop,nandakumar131/hadoop,plusplusjiajia/hadoop,steveloughran/hadoop,apurtell/hadoop,plusplusjiajia/hadoop,JingchengDu/hadoop,apurtell/hadoop