[Merge] lp:~vorlon/goget-ubuntu-touch/uefi into lp:goget-ubuntu-touch

[Steve Langasek]

Now uses oem.Architecture() support from trunk, so I think this is ready for review.

Before merging we should verify whether writing of grub_env works from EFI, without which the a/b failover support won't work correctly.
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https://code.launchpad.net/~vorlon/goget-ubuntu-touch/uefi/+merge/256869
Your team Ubuntu Phablet Team is requested to review the proposed merge of lp:~vorlon/goget-ubuntu-touch/uefi into lp:goget-ubuntu-touch.