ApnPreference: fix editing of APNs

Change-Id: Id04e8dc38f93f47c9356f3d7b67a3b13cca2dad6
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>
Merge remote-tracking branch 'upstream/jb-mr2' into jb-mr2
Merge branch 'jb-mr2' of https://github.com/IOKP/packages_apps_Settings into jb-mr2
PIE (2/2)