Test both IDs for pre-emptive caching.

  When a zone is created the ID is returned and we can
 pre-emptively cache that.  We look for both forms of the ID.
  Explicitly set a key to be `[deleted]`.

  This makes it obvious that a key has been modified, and is
 largely a useful visual reminder.  The value of a deleted
 key will still exist inside a DB_File, so setting it to
 [deleted] allows you to be sure it is really gone.
  Ran perltidy against the test-cases.
  Added functional test-case.

  This uses the Amazon API to create and delete actual zones.
  Allow access to the internal cache-object.
  Added a README file.

  Include it in the distribution.