Cache version key is pulled from env

Author: mcelicalderon

.circleci/config.yml

@@ -20,13 +20,13 @@ jobs:
       - checkout
       - restore_cache:
           keys:
-            - v1.0-<< parameters.gemfile >>-<< parameters.ruby-version >>
+            - {{ .Environment.CACHE_VERSION }}-<< parameters.gemfile >>-<< parameters.ruby-version >>
       - run: gem install bundler -v '1.17'
       - run:
           name: Install dependencies
           command: bundle install
       - save_cache:
-          key: v1.0-<< parameters.gemfile >>-<< parameters.ruby-version >>
+          key: v{{ .Environment.CACHE_VERSION }}-<< parameters.gemfile >>-<< parameters.ruby-version >>
           paths:
             - vendor/bundle
       - run: