Parameterize more YARN/MapReduce memory settings

yarn.app.mapreduce.am.resource.mb
yarn.app.mapreduce.am.command-opts
yarn.scheduler.minimum-allocation-mb
yarn.scheduler.maximum-allocation-mb

This will allow easier memory tuning in accordance with recommendations from
http://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.0.6.0/bk_installing_manually_book/content/rpm-chap1-11.html

Change-Id: Ice2b2a9feea88b7ff27c4430ddd83c83a4db0fbf