init-boot-tpm.sh: Only measure the rootfs if the kernel command line has the 'measureroot' parameter.
Place new 'measureroot' parameter on the kernel command line.
init-boot-tpm.sh: Make ROOT_MODE work as expected.
Fix boot config files to mount the rootfs read-only.
init-boot-tpm.sh: Add debugging break points.
core-image-tpm-initramfs: Set localhost using a function instead of a direct call to echo.

I'm not just doing this for aesthetics. Calling echo directly started
failing. This seems like the right way to do it now.