v0.4.0

1. Fixed an issue that the application may stuck on start. The pn532_uart_wakeup was set to no timeout. Some serial port devices may not respond to any UART command which may lead to the application stuck. The issue is fixed by simply adding a 100 ms timeout. If the device is not responding within 100ms, we will timeout and proceed.
2. Added Salto keys. Salto uses fixed MIFARE Classic keys. Added the Salto keys significantly improved the Salto tags read speed.