Random cleanup patches for the plugins

[Saleem Abdulrasool <compnerd compnerd org>]

Hi.

Attached are a couple of patches to clean up the plugins a slight bit.

They fix the G_DISABLE_DEPRECATED typo and the subsequent fallout.
Additionally, they remove the final lingering bits of libgnome and libgnomeui
references.  The GMemChunk usage also was removed and replaced with the use of
the slice allocator.

These patches remove all of libgnome and libgnomeui usage in seahorse.  It also
allows it to fully build with -Werror and also updates all (glib) API usage to
the most current versions, which is pretty impressive.

-- 
Saleem Abdulrasool
compnerd (at) compnerd (dot) org