Merge pull request #18 from marineam/postinst

add(coreos-*): Add postinst and setgoodroot scripts.
fix(util): Fix detection of the current read-only filesystem.

Switch to stating /usr instead of using ChromeOS's rootdev tool/library.
This should work equally well on both -generic and -usr images.
fix(postinst): Use cgpt from the newly installed image.

The postinst script may depend on the version of cgpt it was built with
so be sure to call it. This is certainly the case in -generic images
which include a cgpt version without support for partition device nodes.
Merge pull request #19 from marineam/usr

fix(util): Fix detection of the current read-only filesystem.
chore(omaha_request_params): remove crufty logic

These special channels mean nothing to me.
feat(omaha_request_params): read /usr/share/coreos/update.conf

Use /usr/share/coreos/update.conf as a second source of info for the
SERVER/GROUP information.
Merge pull request #20 from philips/use-usr-share-coreos-update.conf

feat(omaha_request_params): read /usr/share/coreos/update.conf
feat(omaha): add bootid and machineid

This returns the oem="" and machineid="" field in the app parameters
using the /etc/oem-release file and the /etc/machine-id file
test(*): make all the tests pass

Cleanup all of tests so they pass. It has been months since these tests
have all passed.
fix(omaha_request_action_unittest): always including a machineid

On CoreOS we always include the machineid if available. Delete this
test.
Merge pull request #21 from philips/add-oem-and-machine

feat(omaha): add bootid and machineid
fix(coreos-postinst): Fix mounting ESP partition

Again, goofed up and pipes cannot be used with mapfile (or read) so use
bash process substation instead. Add some safety checks to error if
something goes wrong and there isn't an ESP mount point.
Merge pull request #22 from marineam/fix

fix(coreos-postinst): Fix mounting ESP partition
fix(pxe_update_engine): Sync the mini update engine with recent changes.
add(systemd): Import current units and reboot_manager from overlay.
rename(pxe): Rename pxe services to a more generic "stub" name.

This makes the stub applicable to other diskless images we may add such
as bootable ISOs. Instead of relying on kernel command line options
switching between the real update_engine and the stub is now determined
by a /usr/.noupdate flag file we can include in our images.
fix(update_engine_stub): Set default OEM_ID to "diskless"

Since writing this we've started booting via ISOs so PXE is no longer
the only boot scenario that will trigger this stub.
Merge pull request #23 from marineam/pxe

PXE related updates
fix(update_engine_stub): Avoid a pointless update.conf error.
Merge pull request #25 from marineam/noise

fix(update_engine_stub): Avoid a pointless update.conf error.