Fix some memory leaks.
Fix some memory leaks.

champlain_tile_set_modified_time() now makes a copy of the GTimeVal and frees
it when done.

The property etag is now freed.

Distrotech/libchamplain,potyl/champlain,PabloCastellano/libchamplain,PabloCastellano/libchamplain,PabloCastellano/libchamplain,Distrotech/libchamplain,GNOME/perl-Champlain,StanciuMarius/Libchamplain-map-wrapping,PabloCastellano/libchamplain,GNOME/libchamplain,Distrotech/libchamplain,StanciuMarius/Libchamplain-map-wrapping,GNOME/perl-Gtk2-Champlain,StanciuMarius/Libchamplain-map-wrapping,potyl/champlain,Distrotech/libchamplain,potyl/champlain,PabloCastellano/libchamplain,GNOME/libchamplain,Distrotech/libchamplain,StanciuMarius/Libchamplain-map-wrapping,StanciuMarius/Libchamplain-map-wrapping,GNOME/perl-Champlain,potyl/champlain,GNOME/perl-Gtk2-Champlain