Add meta-mender

[motters]

To allows updating of the CM3 image implement mender into meta-qutipi.

We'll have to ensure we are using the u-boot and that the kernel image type is uImage

Check below for more info:

• https://docs.mender.io/1.3/artifacts/building-mender-yocto-image
• https://github.com/mendersoftware/meta-mender/tree/master/meta-mender-raspberrypi

[motters]

This has been implemented however text appears on boot up which should be hidden. The auto repair and reboot has yet to be tested.

[motters]

https://github.com/QutiPi/meta-qutipi/commit/43a5e5c05c425f5fc9d43b5be9c3bef4826d3928

Auto repair + reboot still to be tested however i'm closing this for now.