do not put file extension in filename (save menu)

[François Boulogne]

Hi,

Current behavior:

When I save a document, the window shows default filename like "Document.jpg"
For some users who are not used to file extensions, they change the file extension by mistake

Expected behavior:

The extension must be hidden in the filename. if multiple file format are possible, then the selector can be used to switch from one format to another.

I also noticed that the default name is "Scanned Document". When I switch to another format with the selector, it becomes "Document". "Document" is a slightly better choice because there is no space in the name.
On archlinux, I noticed that for the french translation, the first default filename is "Document.pdf numérisé", which is problematic. (v 3.18.2, I will check with the last version and keep you updated)

Thank you.

[kosssi (kosssi)]

It'saffect me on xubuntu 16.04 default package