CRM-15706 - Use scope.help() instead of scope.crmUiHelpFile

CRM-15706 - Use scope.help() instead of scope.crmUiHelpFile

The old code relied explicitly passing ```help-id``` string and implicitly
passing a ```crmUiHelpFile``` string through various layers.  This broke
down when trying to implicitly pass crmUiHelpFile through isolate-scopes.

By contrast, this patch relies on explicitly passing a help object. The help
object is complete (i.e.  it has both id and file), so it's easier to pass
through various layers.