fix(test): use singleRun:true for karma tests (#58)

This allows us to run tests from the release script, so that they don't infinitely wait when `yarn
np` invokes `yarn test`.

Author: f2prateek

karma.conf.js

@@ -9,8 +9,11 @@ module.exports = function(config) {
     files: [
       'test/**/*.test.js'
     ],
+    
     browsers: ['PhantomJS'],
 
+    singleRun: true,
+
     middleware: ['server'],
 
     plugins: [