Setting HADOOP_MAPRED_HOME for Apache Hive in CDH

For each user running Hive on MapReduce2 (YARN), make sure that the HADOOP_MAPRED_HOME environment variable is set correctly, as follows:
```
$ export HADOOP_MAPRED_HOME=/usr/lib/hadoop-mapreduce
```
For each user running Hive on MapReduce v1 (MRv1), set the HADOOP_MAPRED_HOME environment variable as follows:
```
$ export HADOOP_MAPRED_HOME=/usr/lib/hadoop-0.20-mapreduce
```