check_ipa_replication should treat status: 1 - Replica Busy as "UNKNOWN" or "OK"

[TJM]

After much discussion with the folks in #freeipa, status of "1" (Replica Busy) should not be considered an error state. At most it should be considered 3 (UKNOWN), but probably should just be considered 0 (OK).

[jlambert121]

Resolved with #19