Install poedit from unstable.

The version we started shipping recently, which is the one our translators want,
is not in Wheezy but in unstable. Then, override our custom backport (in
deb.t.b.o) with the version in unstable.

config/chroot_apt/preferences

@@ -10,6 +10,10 @@ Package: aircrack-ng
 Pin: release o=Debian,a=unstable
 Pin-Priority: 1010
 
+Package: poedit
+Pin: release o=Debian,a=unstable
+Pin-Priority: 1010
+
 Package: xul-ext-torbutton
 Pin: release o=Debian,a=unstable
 Pin-Priority: 999