How do I force NetworkManager to encrypt stored passwords?

In ubuntu 14.04 NetworkManager stores the passwords for networks in the file /etc/NetworkManager/system-connections/<ESSID_of_AP> in plaintext.

I'm not sure if it relies on wpa_supplicant for making the handshake, which I've used to make wireless connections from the command line, and I know for a fact, allows you to store the WPA-PSK in cipher-text. I'm still doing the research now, (It's part of a larger effort) but was wondering if there was a known option, a boolean switch somewhere in the config that I could change to force it to negotiate the handshake with the encrypted value.