style: prefix all test commands with "test-"

It's a style I follow in all my packages...

- test
- test-node
- test-browser
- ...

README.md

@@ -65,7 +65,7 @@ $ npm test
 ### Run integration tests
 
 ```
-$ npm run integration-test
+$ npm run test-integration
 ```
 
 The integration tests use Spectron and Tape. They click through the app, taking screenshots and comparing each one to a reference. Why screenshots?

package.json

@@ -99,12 +99,12 @@
     "build": "buble src --output build",
     "clean": "node ./bin/clean.js",
     "gh-release": "gh-release",
-    "integration-test": "npm run build && node ./test",
     "open-config": "node ./bin/open-config.js",
     "package": "node ./bin/package.js",
     "prepublish": "npm run build",
     "start": "npm run build && electron .",
     "test": "standard && depcheck --ignores=buble,lodash.merge,nodemon,gh-release --ignore-dirs=build,dist && node ./bin/extra-lint.js",
+    "test-integration": "npm run build && node ./test",
     "update-authors": "./bin/update-authors.sh",
     "watch": "nodemon --exec \"npm run start\" --ext js,pug,css --ignore build/ --ignore dist/"
   }