Add rubocop development dependency and code climate configuration. (#794)

* Add rubocop development dependency and code climate configuration.

* Add some rubocop configuration.

* Remove some configuration.

.codeclimate.yml

@@ -0,0 +1,16 @@
+---
+engines:
+  duplication:
+    enabled: true
+    config:
+      languages:
+      - ruby
+  fixme:
+    enabled: true
+  rubocop:
+    enabled: true
+ratings:
+  paths:
+  - "**.rb"
+exclude_paths:
+- spec/

.rubocop.yml

@@ -0,0 +1,11 @@
+AllCops:
+  TargetRubyVersion: 2.4
+  DisplayCopNames: true
+  Exclude:
+    - 'spec/dummy/**/*'
+
+Style/StringLiterals:
+  Enabled: false
+
+Metrics/LineLength:
+  Max: 100

draper.gemspec

@@ -29,4 +29,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'minitest-rails'
   s.add_development_dependency 'capybara'
   s.add_development_dependency 'active_model_serializers', '~> 0.10'
+  s.add_development_dependency 'rubocop'
 end