We no longer need to skip engine linking at install time.

We now have directories to drop engine fragments into instead
of having to rewrite routes.rb and the Gemfile.
Merge pull request #1725 from VictorLowther/pull-req-master-b315146a56209cc5b6a07cb05124133c40dca602

Get admin node deploy working-ish again, and fix a few nits. [5/5]