Prevent needless provider checks
Prevent needless provider checks

- if a hosts DN is listed in ALLOWED_TO_POST, they will be
  allowed to POST regardless of whether they are listed as
  as a provider or not. So why not check ALLOWED_TO_POST
  first and avoid a potentially expensive provider check
- this changes preserves the fact that BANNED_FROM_POST
  overwrites both ALLOWED_TO_POST and any provider lists

apel/rest,apel/rest