add /status endpoint to nodejs server + test
synced code with most recent changes
updated Spark job UI to display the collected metrics in blocks
Merge pull request #645 from caskdata/feature/nodejs-healthcheck

add /status endpoint to nodejs server + test
fixed comments
fixed comments
Merge pull request #662 from cybervisiontech/CDAP-652-spark-job-metrics-blocks

CDAP-652: updated Spark job UI to display the collected metrics in blocks
CDAP-538: Retrieve data from store by byte key.
fixed comments
Merge pull request #660 from cybervisiontech/CDAP-713/HelloWorld-example-archetype

CDAP-713: Update HelloWorld example archetype
Merge remote-tracking branch 'upstream/develop' into CDAP-538-spark-page-rank-app