<1.0 bug> Retries, RetryInterval, and PersistDuration

In order to conform to the W3C Recommended version of XMLSchema, the
following changes should be made to Appendix D:

- Retries should be of type integer, not string.

- RetryInterval should be of type Duration, not string.

- PersistDuration should be of type Duration, not timeDuration.

In addition, the example in section 7.6.4 should be changed accordingly:

- The RetryInterval example should not assume the unit is second.

- The PersistDuration example should look like PT30S. (The P designator
  must always be present; the T designator must be present if any time item
  is present.)

Arvola