fix: add sem-ver

Author: piercus

.travis.yml

@@ -2,12 +2,13 @@ language: node_js
 node_js:
   - '6'
 install:
-  - npm install -g codecov nyc
+  - npm install -g codecov nyc npx
   - npm install
 
 script:
   - npm run lint
   - npm test
 
 after_success:
-  - npm run report-coverage
+  - npm run report-coverage
+  - npx -p node@8 -c "npm run semantic-release"

package.json

@@ -31,6 +31,7 @@
   "devDependencies": {
     "ava": "^0.25.0",
     "bluebird": "^3.5.0",
+    "semantic-release": "^15.1.7",
     "vows": "^0.8.1",
     "xo": "^0.18.2"
   },