Release 2015.10

[Colin Walters <walters verbum org>]

OSTree v2015.10 is now available via this git-evtag[1] signed tag:

https://git.gnome.org/browse/ostree/tag/?h=v2015.10

Matthew Barnes reworked the fetcher to better support fetching commit
history.  This was groundwork for feature work in rpm-ostree to
support deploying specific commits by version.

John Hiesey fixed several important bugs in the static deltas code,
such as ensuring we correctly handle errors from decompression.

Giuseppe Scrivano introduced the concept of a "tombstone" for a commit
that signifies the commit was explicitly deleted on the server side.
The idea here is that an OS vendor may want to have a CI/CD branch but
not keep all history, and this way clients can detect that history was
intentionally truncated.

Following on that, Giuseppe also improved the `prune` commit to
support relative dates with `prune --keep-younger-than=DATE`.

Alexander Larsson introduced "single file" static deltas.  He plans to
use these in xdg-app for convenient *initial* application downloads.
This could also be useful for base OS downloads, e.g. Anaconda
kickstart and the like.

Daniel Drake:
    prepare-root: set up /boot bind-mount for single partition systems

Colin Walters fixed a few bugs, most notable is an embarassing one
where the `ostree init-fs` command used the wrong permissions for
`/tmp`.  This only bit people not using tmpfs-for-tmp and hence wasn't
noticed for a while.

Gatis Paeglis:
    Don't require /boot/uEnv.txt for u-boot support

Leandro Santiago:
      commit: Improve variable name

Thanks to all contributors!

[1] https://github.com/cgwalters/git-evtag