Implement WiFi setup for the Raspberry Pi device

[jbmorley]

Right now the Python / Raspberry Pi device implementation doesn't support the WiFi setup workflow, requiring devices to be manually connected. This won't be too bad once we have a dedicated Raspberry Pi image, but it would still be better if devices could be re-paired.

[jbmorley]

I was experimenting with the access point configuration when setting up pi-gen builds. Could be a useful starting point:

function configure_access_point {

    echo "Configuring network..."
    # Based on the instructions provided at https://github.com/schollz/raspberry-pi-turnkey and
    # https://thepi.io/how-to-use-your-raspberry-pi-as-a-wireless-access-point/.

    cat <<EOF>> "${ROOTFS_DIR}/etc/dhcpcd.conf"
interface wlan0
static ip_address=192.168.4.1/24
EOF

    cat <<EOF>> "${ROOTFS_DIR}/etc/dnsmasq.conf"
interface=wlan0
dhcp-range=192.168.4.2,192.168.4.20,255.255.255.0,24h
EOF

    cat <<EOF>> "${ROOTFS_DIR}/etc/hostapd/hostapd.conf"
interface=wlan0
driver=nl80211
ssid=StatusPanel
hw_mode=g
channel=7
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=StatusPanel
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
EOF

    cat <<EOF>> "${ROOTFS_DIR}/etc/default/hostapd"
DAEMON_CONF="/etc/hostapd/hostapd.conf"
EOF

}