Add bt.qa.fail property to make builds fail or report QA violations

[jonathanaustin]

Similar to bt.qa.skip property that can be used to skip all QA plugins in qa_parent, add a bt.qa.fail property that can be used to make the QA plugins to only report errors or fail the build when a violation is found.

Should default to true to fail the build if QA violations found.

[jonathanaustin]

To also allow the convergence check in qa-parent to be set to fail without overriding the enforcer plugin in bordertech_parent, add a new bt.convergence.check.fail property that can also default to the new bt.qa.fail property.