Deleting a map over the admin page does not delete the underlying files

[kaputtnik]

While working on an other branch i found some bad things:

1. Deleting a map does not removes the underlying files(minimap and mapfile). This is not really problematic since uploading a new file with the same mapname works. But after trying to solve this i found:

2. The column minimap stores a faulty path to the minimap. The problem is here that the path begins with a slash: Trying to use os.path.join fails here because paths beginning with a slash are treated as absolute path and concatenating a base path with the image path fails. It fails because the base path will be omitted when the image path is treated as absolute path (begins with a slash).