Copy contents, not the folder

The `FolderManager#copy_old_shots` method, as it currently stands, copies the old folder **inside** the history folder, if the old folder and the history folder exist. This, in turn, causes all kinds of problems (like not being able to generate gallery files, etc).

The correct way is to copy folder contents is [apparently](http://stackoverflow.com/a/4645159/98634) via an extra `.`