Allow users to use KEEP_LABEL on all resouces subjected by listRemovableResources

[pkremens]

The is no way to prevent Openshift.clean() from deleting these:

		removables.addAll(getUserSecrets());
		removables.addAll(getUserServiceAccounts());
		removables.addAll(getUserRoleBindings());

but it should be doable, e.g.:

	List<HasMetadata> listRemovableResources() {
...
		removables.addAll(getUserSecrets().stream().filter(withoutKeepLabel()).collect(Collectors.toList()));
		removables.addAll(getUserServiceAccounts().stream().filter(withoutKeepLabel()).collect(Collectors.toList()));
		removables.addAll(getUserRoleBindings().stream().filter(withoutKeepLabel()).collect(Collectors.toList()));
		...

		return removables;
	}

	private Predicate<HasMetadata> withoutKeepLabel() {
		return (hasMetadata) -> {
			if (hasMetadata.getMetadata().getLabels() != null) {
				return !(hasMetadata.getMetadata().getLabels().containsKey(KEEP_LABEL));
			} else {
				return true;
			}
		};
	}

[pkremens]

I see now that this is not an issue actually as getUser methods do take the KEEP_LABEL into account, I was fooled by #306. Closing this one.