fix(core_upload_update): use the base image

- Use variable for the image name
- add COREOS prefixed variables so we can start weaning ourself off of the
others.
feat(core_upload_update): insert the public key

shove the public key into the image so it can be found by update_engine
Merge pull request #18 from philips/core_upload_update-signing

Core upload update signing
Merge pull request #19 from marineam/updates

fix(update_ebuilds): Switch default source to rsync mirrors.
feat(build_packages): Add --upload option to build_packages

Defaults to upload for official builds and not otherwise.
fix(bootstrap_sdk): Remove seedcache and snapcache features.

We aren't taking full advantage of seedcache and untarring things isn't
a big burden on us anyway so don't bother and hopefully avoid leaving
oodles of files behind.
Merge pull request #20 from marineam/target

Add ability to upload amd64-generic packages
fix(*): drop FACTORY images

we don't need factory image functionality. Drop it to simplify our
scripts and prepare for our "production" feature and flags.
feat(build*): add CoreOS production image building

This will create a CoreOS production image and support it with the tools
like image_to_vm.sh and build_image.
chore(build_container): delete

This tool was a bit of a hack and isn't really used. Delete it.
fix(image_to_vm.sh): forward fewer ports

we disabled systemd-rest for now so don't tell people to forward all of
those ports.
Merge pull request #21 from philips/building-of-production-coreos-images

Building of production coreos images
fix(build_packages): Fix check for .boto, argument name was wrong.
Merge pull request #22 from marineam/boto

fix(build_packages): Fix check for .boto, argument name was wrong.
fix(common.sh): Correctly report script name in tracebacks

Pretty simple typo.
fix(build_packages): Move gsutil code from build_packages to a library.

To avoid making the same gsutil changes in more scripts move the code to
a library file where some of the basic parts can be shared.
feat(build_image): Add upload support for official builds
fix(bootstrap_sdk): Report the time it took to complete
Merge pull request #23 from marineam/images

Upload official filesystem images
fix(build_library/legacy_disk_layout): Use coreos- prefixes

vboot_reference now recognizes coreos-reserved and coreos-rootfs. Use
these prefixes so we stop using the chromeos GUIDs.

Test-plan: Tested on a VM and it boots and updates.