If migrations are pending, make CurrentSettings use existing values and populate missing columns with defaultssh-refactor-current-settings

master was failing because `ApplicationSetting.create_from_defaults` attempted
to write to a column that did not exist in the database. This occurred in a
`rake db:migrate` task, which was unable to perform the migration that would
have added the missing column in the first place.

In 9.3 RC2, we also had a bug where password sign-ins were disabled because
there were many pending migrations. The problem occurred because
`fake_application_settings` was being returned with an OpenStruct that did not
include the predicate method `signup_enabled?`. As a result, the value would
erroneously return `nil` instead of `true`. This commit uses the values of the
defaults to mimic this behavior.

This commit also refactors some of the logic to be clearer.

1 files changed, 4 insertions, 0 deletions

diff --git a/spec/factories/application_settings.rb b/spec/factories/application_settings.rb
new file mode 100644
index 00000000000..aef65e724c2
--- /dev/null
+++ b/spec/factories/application_settings.rb
@@ -0,0 +1,4 @@
+FactoryGirl.define do
+  factory :application_setting do
+  end
+end