Ability to add comment to document version via webservices

[ShaneH]

In order to make the webservices consistent with the user interface, the ability to add a comment when altering a document (eg using the update command) is required. So if, for example a user updates some field information or tags they can add a comment to the new document version.

In the standard web interface, the "Version Comment" field appears automatically when ever an update is made. Webservices users do not have ANY ability to add the same.