Run tests with Karma test runner

Closes gh-566.

karma.conf.js

@@ -0,0 +1,55 @@
+module.exports = function( config ) {
+  config.set( {
+
+    // Base path, that will be used to resolve files and exclude
+    basePath: "",
+
+    // Frameworks to use
+    frameworks: [ "qunit" ],
+
+    // List of files / patterns to load in the browser
+    files: [
+      "test/bootstrap.js",
+      "js/impress.js",
+      "test/core_tests.js"
+    ],
+
+    // List of files to exclude
+    exclude: [],
+
+    // Test results reporter to use
+    // possible values: 'dots', 'progress', 'junit', 'growl', 'coverage'
+    reporters: [ "progress" ],
+
+    // Web server port
+    port: 9876,
+
+    // Enable / disable colors in the output (reporters and logs)
+    colors: true,
+
+    // Level of logging
+    // possible values: config.LOG_DISABLE || config.LOG_ERROR ||
+    // config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
+    logLevel: config.LOG_DEBUG,
+
+    // Enable / disable watching file and executing tests whenever any file changes
+    autoWatch: true,
+
+    // Start these browsers, currently available:
+    // - Chrome
+    // - ChromeCanary
+    // - Firefox
+    // - Opera (has to be installed with `npm install karma-opera-launcher`)
+    // - Safari (only Mac; has to be installed with `npm install karma-safari-launcher`)
+    // - PhantomJS
+    // - IE (only Windows; has to be installed with `npm install karma-ie-launcher`)
+    browsers: [ "Chrome" ],
+
+    // If browser does not capture in given timeout [ms], kill it
+    captureTimeout: 60000,
+
+    // Continuous Integration mode
+    // if true, it capture browsers, run tests and exit
+    singleRun: false
+  } );
+};