Improve completers generation
convert list to array improvement
Merge remote-tracking branch 'remotes/origin/develop' into completers

Conflicts:
	common-cli/src/main/java/co/cask/common/cli/CommandSet.java
COOPR-523: code improvements
COOPR-523: delete unnecessary lines of code
Merge pull request #7 from cybervisiontech/completers

COOPR-523: Improve completers generation