Add Ubuntu 14.04 Trusty and Debian 8 Jessie support to Debian packaging files.
Upgrade the preferred Nginx version to 1.6.0.
Update passenger_apt_automation invocation command.
The debian:orig_tarball task should fail if downloading the Nginx tarball fails.
Update changelog

[ci:skip]
Ubuntu 14.04 packages should build-depend on ruby2.0 instead of ruby1.8.
Allow Ruby 2.1 as Ruby interpreter in the Debian packages
Merge branch 'trusty'