tracker-preferences: Use Box not HBox which is deprecated
tracker-preferences: Use Box not VBox which is deprecated
tracker-preferences: General glade file clean up and modernisation

Using newer version of glade.
tracker-preferences: Used latest glade and require GTK+ 3.18, fixed tab properties
tracker-preferences: Swap out HScale widgets for Scale with orientation
tracker-preferences: Make the Scale widgets (which were vertical) horizontal

Looks better
tracker-preferences: Added 'control' tab giving more control of what is indexed

Specifically:
- allowing people to disable indexing file content
- allowing indexing of numbers