Add "replace-upload" feature

[akreuzkamp]

I tend not to upload timesheets before monday, because I might work at weekend. I know, I can update the timesheets, but that requires to go to lotsofcake and delete the old timesheet manually.
I would like to be able to add uploading the timesheet to my daily habits as the last thing to do before going home. Ideal would be a one-click "Update loc timesheet" button directly besides "Stop Task", that would open a confirmation dialog ala "Timesheet 4:30h total will be replaced by 30:12h total (+25:42h). Replace?"
You could disable that feature for safety, in case there's more than one timesheet in loc for that week or ask, which one to replace.

I don't know, if loc has API for deleting timesheets, though.

[frankosterfeld]

I think we the new unique installation IDs and staged uploads (Charm uploading daily "drafts" in the background), this will happen automatically when uploading a timesheet for the same week again, with the same installation id.