Add strong_migrations gem to warn when creating unsafe migrations (#5078)

Gemfile

@@ -105,6 +105,7 @@ group :development do
   gem 'brakeman', '~> 3.6', require: false
   gem 'bundler-audit', '~> 0.5', require: false
   gem 'scss_lint', '~> 0.53', require: false
+  gem 'strong_migrations'
 
   gem 'capistrano', '~> 3.8'
   gem 'capistrano-rails', '~> 1.2'

Gemfile.lock

@@ -482,6 +482,8 @@ GEM
       net-scp (>= 1.1.2)
       net-ssh (>= 2.8.0)
     statsd-instrument (2.1.4)
+    strong_migrations (0.1.9)
+      activerecord (>= 3.2.0)
     temple (0.8.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
@@ -614,6 +616,7 @@ DEPENDENCIES
   simplecov (~> 0.14)
   sprockets-rails (~> 3.2)
   statsd-instrument (~> 2.1)
+  strong_migrations
   twitter-text (~> 1.14)
   tzinfo-data (~> 1.2017)
   uglifier (~> 3.2)

config/initializers/strong_migrations.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+StrongMigrations.start_after = 20170924022025 if Rails.env.development?