Add file format version support

Simple header in the form of # EVEMU 1.0 to add to the description format.
Being a comment this means it's ignored for older version of evemu (though
they may still have parsing issues), newer versions can parse it.

Declare current version as 1.0

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>