use yarn for travis

Author: christopherthielen

.gitignore

@@ -2,6 +2,7 @@
 build
 build_packages
 site
+yarn.lock
 
 # common
 **/.*

.travis.yml

@@ -2,14 +2,29 @@ language: node_js
 node_js:
   - "4.1"
 
+cache:
+  yarn: true
+  bundler: true
+  directories:
+    - $HOME/.yarn-cache
+    - $HOME/.cache/yarn
+    - node_modules
+
+before_install:
+  - curl -o- -L https://yarnpkg.com/install.sh | bash
+  - export PATH="$HOME/.yarn/bin:$PATH"
+
+install:
+  - yarn
+
 before_script:
   - export DISPLAY=:99.0
   - sh -e /etc/init.d/xvfb start
-  - npm install -g karma
   - ./nodeserver.sh > /dev/null &
 
 script:
-  - npm run test
+  - tsc
+  - yarn test
 
 sudo: false
 
@@ -18,3 +33,4 @@ git:
 
 notifications:
   slack: angularbuddies:b6leQM9gkBCW0S7MNDsELpqU
+