Add Rubocop

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

test/configuration/volume_test.rb

@@ -3,11 +3,11 @@ require "test_helper"
 class ConfigurationVolumeTest < ActiveSupport::TestCase
   test "docker args absolute" do
     volume = Kamal::Configuration::Volume.new(host_path: "/root/foo/bar", container_path: "/assets")
-    assert_equal ["--volume", "/root/foo/bar:/assets"], volume.docker_args
+    assert_equal [ "--volume", "/root/foo/bar:/assets" ], volume.docker_args
   end
 
   test "docker args relative" do
     volume = Kamal::Configuration::Volume.new(host_path: "foo/bar", container_path: "/assets")
-    assert_equal ["--volume", "$(pwd)/foo/bar:/assets"], volume.docker_args
+    assert_equal [ "--volume", "$(pwd)/foo/bar:/assets" ], volume.docker_args
   end
 end