Zesty Zapus open for development

[Matthias Klose]

Zesty Zapus [1] is now open for development, with syncs from unstable
still running. The development version already starts with some
changes:

- GCC on armhf and arm64 now is built again from the GCC Linaro branch.

- Starting with library transitions: openmpi, boost 1.62.

Please check your uploads in a zesty chroot, don't just test in a xenial or
yakkety environment. See [2] or [3] how to setup such a development chroot.