ostree-releng-scripts v2016.1

[Colin Walters <walters verbum org>]

This is the first release of a new git repo:

https://github.com/ostreedev/ostree-releng-scripts/releases/tag/v2016.1

I suspect for most users, the "do-release-tags" and "rsync-repos"
scripts are going to be the most interesting.

Any contributions welcome.  We're starting to use this in CentOS Atomic SIG:
https://github.com/CentOS/sig-atomic-buildscripts/pull/169