Add Rubocop

- Pull in the 37signals house style
- Autofix violations
- Add to CI

test/cli/healthcheck_test.rb

@@ -64,10 +64,10 @@ class CliHealthcheckTest < CliTestCase
     end
     assert_match "container not ready (unhealthy)", exception.message
   end
-  
+
   test "raises an exception if primary does not have traefik" do
     SSHKit::Backend::Abstract.any_instance.expects(:execute).never
-    
+
     exception = assert_raises do
       run_command("perform", config_file: "test/fixtures/deploy_workers_only.yml")
     end
@@ -77,6 +77,6 @@ class CliHealthcheckTest < CliTestCase
 
   private
     def run_command(*command, config_file: "test/fixtures/deploy_with_accessories.yml")
-      stdouted { Kamal::Cli::Healthcheck.start([*command, "-c", config_file]) } 
+      stdouted { Kamal::Cli::Healthcheck.start([ *command, "-c", config_file ]) }
     end
 end