Update Circle.yml with more caching

packages/react-navigation/circle.yml

@@ -1,17 +1,28 @@
 machine:
   node:
     version: 6
-  pre:
-    - mkdir ~/.yarn-cache
+  environment:
+    PATH: "${PATH}:${HOME}/${CIRCLE_PROJECT_REPONAME}/node_modules/.bin"
 
 dependencies:
   pre:
     - curl -o- -L https://yarnpkg.com/install.sh | bash
   cache_directories:
-    - "~/.yarn-cache"
+    - ~/.cache/yarn
+    - ./website/node_modules
+    - ./examples/NavigationPlayground/node_modules
+    - ./examples/ReduxExample/node_modules
   override:
-    - yarn install
-    - cd website && yarn install
+    - yarn
+    - cd website && yarn
+    - cd examples/NavigationPlayground && yarn add file:../.. && yarn 
+    - cd examples/ReduxExample && yarn add file:../.. && yarn 
+
+test:
+  post:
+    - yarn codecov
+    - cd examples/NavigationPlayground && yarn test
+    - cd examples/ReduxExample && yarn test
 
 deployment:
   website-prod:
@@ -19,9 +30,3 @@ deployment:
     commands:
       - yarn run build-docs
       - ./scripts/deploy-website.sh
-
-test:
-  post:
-    - yarn codecov
-    - cd examples/NavigationPlayground && yarn add file:../.. && yarn install && yarn test
-    - cd examples/ReduxExample && yarn add file:../.. && yarn install && yarn test