Release 2016.1

[Colin Walters <walters verbum org>]

OSTree v2016.1 is now available via this git-evtag[1] signed git tag:

https://git.gnome.org/browse/ostree/tag/?h=v2016.1

Notable commits:

* Alexander Larsson contributed changes to better isolate concurrent use of
  OSTree pulls into the same repository:

      repo: Use per-transaction staging dir
      repo: Allocate a tmpdir for each OstreeFetcher to isolate concurrent downloads

* Colin Walters added two new APIs that make it easier to optimize
  committing new trees from previously generated content:

      repo: Expose dfd-relative mtree writes as public API
      repo: Add APIs for devino optimization between checkout -> commit

  and contributed build fixes as well as internal optimizations for deployment writing.

* Giuseppe Scrivano enhanced the prune command:

      prune: add new flag --static-deltas-only

* Jonathan Lebon made `grub2-mkconfig` work reliably when *not* run by OSTree:

      grub2_generate: load sysroot before using it

* Matthew Barnes added a new remote command:

      remote: Add "ostree remote summary" command

  and contributed several other cleanups inside the HTTP fetcher.


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