Don't step on Halium

[UniversalSuperBox]

A Halium build tree should, in theory, be able to make Halium images even though ubports-boot is present. This is not currently possible in the current implementation.

These are the issues that must be fixed to coexist in a Halium tree:

• Block device nodes with friendly names should be in /dev/block rather than /dev itself #1 Block device nodes with friendly names should be in /dev/block rather than /dev itself
• Find and use a better way to embed the userdata partition #2 Write a better way to embed the /data partition
• hybris-boot won't boot when ubports-boot is in the source tree. #3 hybris-boot won't boot when ubports-boot is in the source tree

This issue should be closed when it is possible to build working ubports-boot and hybris-boot images from the same Halium source tree without modifying any device sources.