v2.7.0

This release updates the system to use Buildroot 2020.05 and Erlang/OTP 23.
Please see the respective release notes for updates and deprecations in both
projects for changes that may affect your application.

• New features

  • Enable WiFi mesh support in the 802.11 stack
  • NervesKey support (see README.md for device tree overlay information)
  • Added support for the PowerVR SGX graphics accelerator

• Updated dependencies

  • nerves_system_br v1.12.0
  • Erlang/OTP 23.0.2
  • Linux 4.19.120 with Beagleboard kernel patches