Add rubocop

Adds rubocop with a basic ruleset that can be run in the following ways:

* `rubocop` - will run checks against codebase
* `rubocop -a` - will run checks and fix what it can
* `rake` - will run autocorrect (`rubocop -a`) and specs

CI now runs rubocop and specs as two separate (and parallel) tasks, so we can see discrete passes and failures on PRs.

Also fixes existing rubocop failures.

.circleci/config.yml

@@ -1,39 +1,75 @@
----
+# Ruby CircleCI 2.0 configuration file
+#
+# Check https://circleci.com/docs/2.0/language-ruby/ for more details
+#
+
+defaults: &defaults
+  working_directory: ~/repo
+  docker:
+  - image: circleci/ruby:2.5.3-node-browsers
+
 version: 2
 jobs:
-  build:
-    parallelism: 3
-    working_directory: ~/repo
+  install_dependencies:
+    <<: *defaults
+    steps:
+    - checkout
+    - restore_cache:
+        keys:
+        - v1-dependencies-{{ checksum "Gemfile.lock" }}
+        - v1-dependencies-
+    - run: bundle install --jobs=4 --retry=3 --path vendor/bundle
+    - save_cache:
+        paths:
+        - ./vendor/bundle
+        key: v1-dependencies-{{ checksum "Gemfile.lock" }}
+
+  run_checks:
+    <<: *defaults
+    steps:
+    - checkout
+    - restore_cache:
+        keys:
+        - v1-dependencies-{{ checksum "Gemfile.lock" }}
+        - v1-dependencies-
+    - run: bundle --path vendor/bundle
+    - run: bundle exec rubocop
+
+  run_tests:
+    <<: *defaults
     docker:
-      - image: circleci/ruby:2.5.1-node-browsers
+    - image: circleci/ruby:2.5.3-node-browsers
     steps:
-      - checkout
-      # Restore Cached Dependencies
-      - restore_cache:
-          name: Restore bundle cache
-          key: v1-cfa_styleguide-{{ checksum "Gemfile.lock" }}
-      # Bundle install dependencies
-      - run: bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3 --full-index
-      # Cache Dependencies
-      - save_cache:
-          name: Store bundle cache
-          key: v1-cfa_styleguide-{{ checksum "Gemfile.lock" }}
-          paths:
-            - vendor/bundle
-      # Create place to store test results
-      - run: mkdir /tmp/test-results
-      # Run the tests
-      - type: shell
-        command: |
-          gem install rspec && \
-          bundle exec rspec --profile 10 \
-                            --require ./spec/support/pre_documentation_formatter.rb \
-                            --format RspecJunitFormatter \
-                            --out /tmp/test-results/rspec.xml \
-                            --format PreDocumentationFormatter \
-                            $(circleci tests glob "spec/**/*_spec.rb" | circleci tests split --split-by=timings)
-      - store_test_results:
-          path: /tmp/test-results
-      - store_artifacts:
-          path: spec/test_app/tmp/screenshots
-          destination: screenshots
+    - checkout
+    - restore_cache:
+        keys:
+        - v1-dependencies-{{ checksum "Gemfile.lock" }}
+        - v1-dependencies-
+    - run: bundle --path vendor/bundle
+    - run: mkdir /tmp/test-results
+    - type: shell
+      command: |
+        bundle exec rspec --profile 10 \
+                          --require ./spec/support/pre_documentation_formatter.rb \
+                          --format RspecJunitFormatter \
+                          --out /tmp/test-results/rspec.xml \
+                          --format PreDocumentationFormatter \
+                          $(circleci tests glob "spec/**/*_spec.rb" | circleci tests split --split-by=timings)
+    # collect reports
+    - store_test_results:
+        path: /tmp/test-results
+    - store_artifacts:
+        path: spec/test_app/tmp/screenshots
+        destination: screenshots
+
+workflows:
+  version: 2
+  build:
+    jobs:
+    - install_dependencies
+    - run_checks:
+        requires:
+        - install_dependencies
+    - run_tests:
+        requires:
+        - install_dependencies