Adds .travis.yml and gulp test task

This commit also updates karam to 0.13.22 to avoid
karma-runner/karma#1782 (sockets.forEach is not a function)
when running gulp test.

.travis.yml

@@ -0,0 +1,5 @@
+language: node_js
+node_js:
+  - "4.4.3"
+before_install:
+  - npm install -g gulp

gulp/tasks/test.js

@@ -0,0 +1,13 @@
+var gulp = require('gulp');
+var Server = require('karma').Server;
+var path = require('path');
+
+/**
+ * Run test once and exit
+ */
+gulp.task('test', function (done) {
+  new Server({
+    configFile: path.resolve(__dirname, '../../karma.conf.js'),
+    singleRun: true
+  }, done).start();
+});

package.json

@@ -19,7 +19,8 @@
   ],
   "scripts": {
     "start": "node app.js",
-    "postinstall": "gulp build --prod"
+    "postinstall": "gulp build --prod",
+    "test": "gulp test"
   },
   "keywords": [
     "dillinger",
@@ -110,7 +111,7 @@
     "htmlparser2": "^3.8.3",
     "jshint-stylish": "^1.0.0",
     "json-loader": "^0.5.1",
-    "karma": "0.13.10",
+    "karma": "0.13.22",
     "karma-chrome-launcher": "^0.1.5",
     "karma-jasmine": "^0.1.5",
     "karma-phantomjs-launcher": "^0.1.4",