tracker: Correctly set "title-from-filename"
tracker: Correctly set "title-from-filename"

Tracker usually provides us with a title that's derived from the
filename. Replicate its process to create a title from a filename
to check if the title is actually set from the filename.

This allows the local-metadata plugin to parse it to remove gunk, and
other plugins to override its throwaway title.

https://bugzilla.gnome.org/show_bug.cgi?id=740756

MikePetullo/grilo-plugins,GNOME/grilo-plugins,grilofw/grilo-plugins,MathieuDuponchelle/grilo-plugins,grilofw/grilo-plugins,MikePetullo/grilo-plugins,jasuarez/grilo-plugins,GNOME/grilo-plugins,MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,jasuarez/grilo-plugins,MikePetullo/grilo-plugins,MathieuDuponchelle/grilo-plugins