v0.4.2

WiFi configuration is easier now! To scan for networks, run
VintageNetWiFi.quick_scan and then to connect, run
VintageNetWiFi.quick_configure("ssid", "password").

Updates:

• Update Nerves systems to the latest (nerves_system_br v1.13.7-based)
• Update circuits_i2c so that it includes the new discover_* helper
  functions
• Update vintage_net_wifi to pull in the "quick" helper functions