Use Particle without WIFI

ref:
https://community.particle.io/t/can-a-photon-boot-without-wifi/17685/7
https://community.particle.io/t/solved-make-photon-run-code-without-being-necessarily-connected-to-the-particle-cloud/25953/2
https://community.particle.io/t/using-photon-without-internet-connection/19061/3
https://docs.particle.io/reference/firmware/photon/#manual-mode