Code review comment for lp:~newell-jensen/curtin/add-arm64-support

comments remaining:
 - if user specifies 'simple-boot', but is_uefi_bootable, they will get uefi. that seems possibly wrong
 - boot is passed around in helpers/common as a number. makes more sense to be a boolean, no? use 'true' or 'false' as values.
 - i dont think i like having partitioning_commands['builtin'] being dynamic.
   I think i'd rather just have 'simple' do the right thing, but let a user provided config explicitly set that.
    Also, config can be set on the command line, so:
      curtin install --set block-meta/boot-partition/enabled=True
    is the same as you have here with:
      curtin block-meta --boot

I've just proposed merging:
 bzr+ssh://bazaar.launchpad.net/~smoser/curtin/add-arm64-support/
into here. It has some cleanups. the config based approach isn't completely done there.