PHP-942: Throw MongoDuplicateKeyException on duplicate key errors
11001 and 12582 are also valid duplicatekey error codes
Add the error code into the test, per pr review
Merge pull request #559 from bjori/PHP-942-duplicate-key-exception

PHP-942: Throw MongoDuplicateKeyException on duplicate key errors

* bjori/PHP-942-duplicate-key-exception:
  Add the error code into the test, per pr review
  11001 and 12582 are also valid duplicatekey error codes
  PHP-942: Throw MongoDuplicateKeyException on duplicate key errors