#44 Use comments when naming versions

[edh]

When recovering an existing file, currently the list of versions available are simply named by the SVN revision number. This can be confusing and is unhelpful.

A better behaviour would be to take the comment entered upon import/commit and tag these onto the version numbers. Eg. 1234-initial-import, 1235-incremental-save. This would make it easier for a user to tell which version they wanted. Date/time are not required as these are already set on the version files when they are generated.