Release version 1.12.0

This release improves support for secure clusters by setting up some YARN and JHS directories in HDFS for multi-user usage.

• Support yarn.app.mapreduce.am.staging-dir ( Issue: #150 )
• Support mapreduce.jobhistory.done-dir and mapreduce.jobhistory.intermediate-done-dir ( Issue: #151 )
• Tests for #135 and #150 ( Issue: #152 )