* Bump `Version` field.
* Set minimum nginx version to 1.4.6, per #1654
* Depend on both `rubygem-foo` (Ubuntu) and `ruby-foo` (Debian).
* Add distro-default `docker.io (>= 1.6.2)` as an alternative.
Version 1.6.2 is in both `trusty-updates` and `jessie-backports`,
while `trusty` itself has `0.9.1`. We seriously want to avoid that.
This also updates the docs so people don't forget to bump the version
field in the future. Even though we really do that for them with sed.
This will allow developers to run an `upgrade` on existing installations without breaking because docker-engine isn't yet in their apt lists...
[ci skip]
This should allow installation of the dokku packages on debian jessie. Upstream docker created this package in response to an issue where `cgroup-bin` could not be installed at the same time as lxc.
Closes#1236
Refs #1076
[ci skip]
