Add support for Rubocop and Hound CI.

.hound.yml

@@ -0,0 +1,27 @@
+---
+# Too picky.
+LineLength:
+  Enabled: false
+
+# This should truly be on for well documented gems.
+Documentation:
+  Enabled: false
+
+# Neatly aligned code is too swell.
+SingleSpaceBeforeFirstArg:
+  Enabled: false
+
+# Don't mess with RSpec DSL.
+Blocks:
+  Exclude:
+    - 'spec/**/*'
+
+# Single quotes are default in Rubocop.
+StringLiterals:
+  EnforcedStyle: single_quotes
+
+SignalException:
+  Enabled: false
+
+ClassAndModuleChildren:
+  Enabled: false

.rubocop.yml

@@ -0,0 +1,8 @@
+---
+inherit_from: .hound.yml
+
+AllCops:
+  Exclude:
+    - spec/dummy/**/*
+    - bin/*
+    - Guardfile

spree_email_to_friend.gemspec

@@ -41,4 +41,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'ffaker', '>= 1.25.0'
   s.add_development_dependency 'guard-rspec', '>= 4.3.1'
   s.add_development_dependency 'pry-rails', '>= 0.3.2'
+  s.add_development_dependency 'rubocop', '>= 0.24.1'
 end