.travis.yml: Update to newer travis config. Adds running tests

Author: daurnimator

.travis.yml

@@ -1,12 +1,23 @@
-language: node
+sudo: false
+dist: trusty
+language: node_js
 
 cache: yarn
 
-install:
-  - yarn
+matrix:
+  include:
+    - node_js: 8
+    - node_js: node
+
+before_install:
+  - 'if [[ `npm -v` != 5* ]]; then npm i -g npm@^5.0.0; fi'
+  - nvm --version
+  - node --version
+  - npm --version
 
 script:
   - yarn lint
+  - yarn test
 
 notifications:
   email: false