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.
doc/devguide/testing: Add missing references to railties:install:migrations rake test
dev: fix errors in pull-requests builds from Dell private builds
dev: builds_for_pull_request(): rename res to builds_for_release

This is a complex function, so let's avoid cryptic variable names
which make it harder to understand
dev: builds_for_pull_request(): rename id to pr_id

This is a complex function, so let's avoid cryptic variable names
which make it harder to understand.  Also id is reused for different
things later in the function.
dev: builds_for_pull_request(): rename build_tmp to valid_builds

This is a complex function, so let's avoid cryptic variable names
which make it harder to understand.
dev: builds_for_pull_request(): rename id to build

This is a complex function, so let's avoid cryptic variable names
which make it harder to understand.
dev: builds_for_pull_request(): rename p to parent_build

This is a complex function, so let's avoid cryptic variable names
which make it harder to understand.
Merge pull request #1727 from aspiers/fix/pull-requests-builds

Merged by devtool for VictorLowther
Merge pull request #1728 from aspiers/fix/engine-migrations

Merged by devtool for VictorLowther
travis-ci/update-git.sh: add new options to aid debugging
Merge pull request #1730 from aspiers/topic/update-git-options

travis-ci/update-git.sh: add options to aid debugging
Merge pull request #1725 from VictorLowther/pull-req-master-b315146a56209cc5b6a07cb05124133c40dca602

Get admin node deploy working-ish again, and fix a few nits. [5/5]
Merge pull request #1733 from aabes/master

Merged by devtool for VictorLowther