fix incorrect usages of ByteBuffer.array()

Conflicts:
	cdap-client-tests/src/test/java/co/cask/cdap/client/app/FakeFlow.java
better impl of Bytes.toString()
CDAP-562 Ensure HDFS delegation token is updated
Merge pull request #600 from caskdata/feature/cherry-pick-bb-array

Feature/cherry pick bb array
Merge pull request #603 from caskdata/hotfix/hdfs-token

CDAP-562 Ensure HDFS delegation token is updated
WIP
Merge branch 'feature/fix-spark-classloader' of github.com:caskdata/cdap into feature/fix-spark-classloader