feat(update_ebuilds): Add option to immediately commit updates
add(update_distfiles): New script to build and upload a distfiles mirror

This script wraps emirrordist to scan all ebuilds and fetch every
SRC_URI to construct a distfiles mirror. It can then optionally upload
to storage.core-os.net via gsutil.

Note: This is a work-in-progress, emirrordist expects to operate on a
complete mirror on the local filesystem but maintaining a complete local
copy of everything is burdensome. Before this is truly practical a
modified version of emirrordist will be needed to either accept a list
of already-uploaded files it can assume are OK or operate on the cloud
storage system directly.
Merge pull request #7 from marineam/mirror

Mirror