Fixes#10744
Fixes:
./bin/node.sh: 44: ./bin/node.sh: source: not found
Could not find java - please run /opt/druid/apache-druid-0.20.0/bin/verify-java to confirm it is installed.
* Allow startup scripts to specify java home
The startup scripts now look for java in 3 locations. The order is from
most related to druid to least, ie
${DRUID_JAVA_HOME}
${JAVA_HOME}
${PATH}
* Update fn names and clean up code
* final round of fixes
* fix spellcheck
Michka Popoff
Suneet Saldanha
Clint Wylie
Gian Merlino
Charles Allen