Imports must replace drafts w/ published in split

PLAT_299

@adampalay please review & decide whether to add another bug report for old mongo (which does not work)
any(@cpennington @doctoryes @nasthagiri) please review
So, I believe old mongo has both this existing bug and fails at "If a module is in draft in the destination course, but is not in the imported course, after importing I'd think the module in the destination course should not be in draft." This fix makes split act the way you're saying.