Enable rubocop rules in config and seed files

We were unintentionally ignoring them while trying to ignore just the
schema file, migration files, and initializers generated with `rails
generate`

.rubocop_basic.yml

@@ -7,9 +7,8 @@ AllCops:
     - "**/Rakefile"
     - "**/config.ru"
   Exclude:
-    - "db/**/*"
-    - "config/**/*"
-    - "script/**/*"
+    - "db/migrate/**/*"
+    - "db/schema.rb"
   TargetRubyVersion: 2.3
   # RuboCop has a bunch of cops enabled by default. This setting tells RuboCop
   # to ignore them, so only the ones explicitly set in this file are enabled.