fix(ci): use yarn in travis

Author: Introvertuous

.travis.yml

@@ -9,11 +9,11 @@ node_js:
   - '8'
   - '6'
 script:
-  - npm run build
+  - yarn build
 after_success:
-  - npm run travis-deploy-once "npm run semantic-release"
-  - npm run build-example
-  - npm run deploy-example
+  - yarn travis-deploy-once "yarn semantic-release"
+  - yarn build-example
+  - yarn deploy-example
 branches:
   except:
     - /^v\d+\.\d+\.\d+$/

package.json

@@ -52,9 +52,9 @@
     "semantic-release": "semantic-release",
     "build": "rollup -c",
     "start": "rollup -c -w",
-    "build-example": "cd example && npm install && npm run build",
-    "deploy-example": "npm run build-example && gh-pages -d ./example/build",
-    "analyze": "npm run build && webpack-bundle-analyzer dist/index.js"
+    "build-example": "cd example && yarn && yarn build",
+    "deploy-example": "gh-pages -d ./example/build",
+    "analyze": "webpack-bundle-analyzer dist/index.js"
   },
   "files": [
     "dist"