JIRA: https://jira.springsource.org/browse/INT-4334 * Add a `DirectoryScanner` setter named `setScanner` in `AbstractInboundFileSynchronizingMessageSource` to set the `FileReadingMessageSource`'s scanner. * Add tests to `AbstractRemoteFileSynchronizerTests`. Polish. Updates xsd, tests and documentation. Fix xsd formatting. Addresses review comments. * Some code style polishing