v1.22

Mos tool:

• Fix aws thing name for the cases when it's not the default <arch>_<mac>

Firmware:

• BT: Add API for managing pairing; improve security
• ESP32: update ESP-IDF
• ota-aws-shadow library improved and renamed to ota-shadow
• Add events API, see mgos_event.h
• Add wifi.ap.hostname: e.g. if it's set to foo.com, then all clients connected to the device's wifi AP
  would be able to use the hostname foo.com instead of the device's IP 192.168.4.1.