... and these steps are also necessary to be able to fully use Network Manager:
Add user to the netdev group.
Create /etc/polkit-1/localauthority/50-local.d/org.freedesktop.NetworkManager.pkla with these settings:
[nm-applet] Identity=unix-group:netdev Action=org.freedesktop.NetworkManager.* ResultAny=yes ResultInactive=no ResultActive=yes