fix(init): karma paths reflect sourceDir config

Fixes angular#1683

Author: Brocco

addon/ng2/blueprints/ng2/files/config/karma.conf.js

@@ -19,10 +19,10 @@ module.exports = function (config) {
       }
     },
     files: [
-      { pattern: './src/test.ts', watched: false }
+      { pattern: './<%= sourceDir %>/test.ts', watched: false }
     ],
     preprocessors: {
-      './src/test.ts': ['angular-cli']
+      './<%= sourceDir %>/test.ts': ['angular-cli']
     },
     remapIstanbulReporter: {
       reports: {