Update kafo to 0.3.16
Add build-essential to foreman-core deps
fixes #4739 - add dependency on libaugeas-ruby

The problem on Debian/wheezy is, that foreman-proxy is running under
Ruby 1.9 (system default), but puppet is on version 2.7.x, which has no
support for ruby >1.8, so the dependency on puppet does pull in only
libaugeas-ruby1.8.