Replace govuk-lint

- The GOV.UK Lint gem is deprecated in favour of using Rubocop directly
  with a set of shared configs.
- See https://github.com/alphagov/govuk-rfcs/pull/ 100 for more context.

https://trello.com/c/CdBFg6yw/1521-replace-govuk-lint-with-rubocop-govuk

.rubocop.yml

@@ -0,0 +1,3 @@
+inherit_gem:
+  rubocop-govuk:
+    - config/default.yml

Gemfile

@@ -13,7 +13,7 @@ group :production, :staging do
 end
 
 group :development, :test do
-  gem "govuk-lint"
+  gem "rubocop-govuk"
 end
 
 group :test do

Gemfile.lock

@@ -11,14 +11,8 @@ GEM
     diff-lcs (1.3)
     faraday (0.15.3)
       multipart-post (>= 1.2, < 3)
-    ffi (1.11.1)
-    govuk-lint (4.0.1)
-      rubocop (~> 0.72)
-      rubocop-rails (~> 2)
-      rubocop-rspec (~> 1.28)
-      scss_lint
     hashdiff (1.0.0)
-    jaro_winkler (1.5.3)
+    jaro_winkler (1.5.4)
     kgio (2.11.2)
     method_source (0.9.0)
     multipart-post (2.0.0)
@@ -40,9 +34,6 @@ GEM
     rainbow (3.0.0)
     raindrops (0.19.0)
     rake (12.3.3)
-    rb-fsevent (0.10.3)
-    rb-inotify (0.10.0)
-      ffi (~> 1.0)
     rspec (3.7.0)
       rspec-core (~> 3.7.0)
       rspec-expectations (~> 3.7.0)
@@ -56,31 +47,27 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.7.0)
     rspec-support (3.7.1)
-    rubocop (0.75.0)
+    rubocop (0.76.0)
       jaro_winkler (~> 1.5.1)
       parallel (~> 1.10)
       parser (>= 2.6)
       rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 1.7)
+    rubocop-govuk (1.0.0)
+      rubocop (~> 0.76)
+      rubocop-rails (~> 2)
+      rubocop-rspec (~> 1.28)
     rubocop-rails (2.3.2)
       rack (>= 1.1)
       rubocop (>= 0.72.0)
     rubocop-rspec (1.36.0)
       rubocop (>= 0.68.1)
     ruby-progressbar (1.10.1)
     safe_yaml (1.0.5)
-    sass (3.7.4)
-      sass-listen (~> 4.0.0)
-    sass-listen (4.0.0)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
     sawyer (0.8.1)
       addressable (>= 2.3.5, < 2.6)
       faraday (~> 0.8, < 1.0)
-    scss_lint (0.58.0)
-      rake (>= 0.9, < 13)
-      sass (~> 3.5, >= 3.5.5)
     sinatra (2.0.4)
       mustermann (~> 1.0)
       rack (~> 2.0)
@@ -105,12 +92,12 @@ PLATFORMS
 
 DEPENDENCIES
   climate_control (~> 0.2)
-  govuk-lint
   octokit (~> 4.3)
   pry (~> 0.11.3)
   rack-test (~> 0.8.0)
   rake (~> 12.3.0)
   rspec (~> 3.7.0)
+  rubocop-govuk
   sinatra
   slack-poster (~> 2.2)
   timecop (~> 0.9.1)