Sync status for file sync commands

[OscarCreator]

It could be good to have sync status message from file syncing (RsyncDownFile and RsyncUpFile). There is already a status variable which can be seen if RsyncProjectConfig is run but no predefined status message exists.

• create predefined status message which can be retrieved by a lua command require("rsync").xxx.status()
• add config option to override this deafult message with a custom function
• add example to README and docs on how customize message