Add basic invoices setup

.rubocop.yml

@@ -14,13 +14,16 @@ Metrics/BlockLength:
   Exclude:
     - 'spec/**/*'
 
-# The next 3 rubocop enabled disallow visual alignment (EasyAlign)
+# The next 4 rubocop enabled disallow visual alignment (EasyAlign)
 Layout/ExtraSpacing:
   Enabled: false
 Layout/HashAlignment:
   Enabled: false
 Layout/SpaceBeforeFirstArg:
   Enabled: false
+Layout/SpaceInsideParens:
+  Exclude:
+    - 'spec/**/*'
 
 Layout/SpaceInsideHashLiteralBraces:
   Enabled: false