HADOOP-282.  Fix datanode to retry registration, rather than permanently fail if the namenode is down when it starts.  Contributed by Owen.
HADOOP-282.  Fix datanode to retry registration, rather than permanently fail if the namenode is down when it starts.  Contributed by Owen.

git-svn-id: 4d48d1092ee340c9ada5711cdbe4355b138bc22b@412545 13f79535-47bb-0310-9956-ffa450edef68

awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop,awylie/hadoop