IMPALA-6394: Restart HDFS when blocks are under replicated
IMPALA-6394: Restart HDFS when blocks are under replicated

HDFS sometimes fails to fully replicate all the blocks in 30 seconds
and no progress is made. This patch tries to restart HDFS several times
before aborting the data loading.

Change-Id: Iefd4c2fc6c287f054e385de52bdc42b0bdbd7915
Reviewed-on: http://gerrit.cloudera.org:8080/9469
Reviewed-by: Alex Behm <fe1626037acfc2dc542d2aa723a6d14f2464a20c@cloudera.com>
Tested-by: Impala Public Jenkins

cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala