bindings: update libnotify binding

Also add a new metadata for _get_server_caps() return value

https://bugzilla.gnome.org/show_bug.cgi?id=710838
gio-2.0: Fix uint8[]/char** types for contents parameters for g_file_[load|replace]_contents()

https://bugzilla.gnome.org/show_bug.cgi?id=710867
glib-2.0: Fix type of g_hash_table_iter_next() parameters to always be gpointer

https://bugzilla.gnome.org/show_bug.cgi?id=710868
Fix memory leak when assigning an owned gvariant to an unowned variable

Fixes bug 710882.
Revert "gio-2.0: Fix uint8[]/char** types for contents parameters for g_file_[load|replace]_contents()"

This reverts commit e4ef6fb72f560da385a09d262ef8afd2b64a1fc8.
gio-2.0: Update. New Notification and Subprocess api

Based on patch by Florian Müllner.

Fixes bug 710912.