Fix gnome attachment status schema

Index names should mention proper table name - error probably due to
copy-pasta.

Also set some non-empty string as a default value for not null
description column - I remember oracle db making some fuss over it
(like converting empty strings to NULLs).
Update attachment status field names and descriptions

For now do not try to have nice, spaced names - it might break some
external tools.

Descriptions are taken from the table dump.