$ cat network/interfaces
# Loopback
auto lo
iface lo inet loopback

# 10/100 Ethernet
auto eth0
iface eth0 inet dhcp

# Wireless
auto wlan0
# Roaming Configuration
iface wlan0 inet manual
   wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

iface default inet dhcp

$ cat wpa_supplicant/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
        ssid="YOUR SSID HERE"
        #proto=RSN
        #key_mgmt=WPA-PSK
        #pairwise=CCMP
        #group=CCMP
        psk=YOUR HASHED PASSWORD HERE
}

network={
        key_mgmt=NONE
}