Add rubocop-rspec gem and require it at rubocop config

.rubocop.yml

@@ -1,4 +1,5 @@
 inherit_from: .rubocop_todo.yml
+require: rubocop-rspec
 
 AllCops:
   DisplayCopNames: true

Gemfile

@@ -88,6 +88,7 @@ group :development do
   gem 'capistrano3-delayed-job', '~> 1.7.3'
   gem 'mdl', '~> 0.4.0', require: false
   gem 'rubocop', '~> 0.52.1', require: false
+  gem 'rubocop-rspec', '~> 1.21.0', require: false
   gem 'rvm1-capistrano3', '~> 1.4.0', require: false
   gem 'scss_lint', '~> 0.54.0', require: false
   gem 'web-console', '~> 3.3.0'

Gemfile.lock

@@ -301,7 +301,7 @@ GEM
       cocaine (~> 0.5.5)
       mime-types
       mimemagic (~> 0.3.0)
-    parallel (1.11.2)
+    parallel (1.12.1)
     paranoia (2.4.0)
       activerecord (>= 4.0, < 5.2)
     parser (2.4.0.2)
@@ -382,14 +382,16 @@ GEM
       rspec-mocks (~> 3.6.0)
       rspec-support (~> 3.6.0)
     rspec-support (3.6.0)
-    rubocop (0.49.1)
+    rubocop (0.52.1)
       parallel (~> 1.10)
-      parser (>= 2.3.3.1, < 3.0)
+      parser (>= 2.4.0.2, < 3.0)
       powerpack (~> 0.1)
-      rainbow (>= 1.99.1, < 3.0)
+      rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (~> 1.0, >= 1.0.1)
-    ruby-progressbar (1.8.1)
+    rubocop-rspec (1.21.0)
+      rubocop (>= 0.52.0)
+    ruby-progressbar (1.9.0)
     rubyzip (1.2.1)
     rvm1-capistrano3 (1.4.0)
       capistrano (~> 3.0)
@@ -552,7 +554,8 @@ DEPENDENCIES
   rinku (~> 2.0.2)
   rollbar (~> 2.15.5)
   rspec-rails (~> 3.6)
-  rubocop (~> 0.49.1)
+  rubocop (~> 0.52.1)
+  rubocop-rspec (~> 1.21.0)
   rubyzip (~> 1.2.0)
   rvm1-capistrano3 (~> 1.4.0)
   sass-rails (~> 5.0, >= 5.0.4)