Add junit test for set-external-build-result CLI command

Bump parent pom version to 1.511. We need even higher to get CLICommandInvoker
class for granted. However, since parent pom 1.512 version both legacy and new
unit test frameworks are broken: TopLevelItemDescriptor can not be retrieved
any more. As a work around copy temporary CLICommandInvoker in our test and
remove it once the problem with unit test framework is ssolved.