fix: correctly use yarn when it is present

Now importing execSync from child_process correctly.

closes #11

Author: juancarlosfarah

.gitignore

@@ -38,3 +38,6 @@ cypress
 # exclude coverage
 /coverage
 .nyc_output
+
+# exclude directories used to test command outputs
+/output

src/initStarter.js

@@ -1,5 +1,5 @@
 import path from 'path';
-import execSync from 'child_process';
+import { execSync } from 'child_process';
 import execa from 'execa';
 import fs from 'fs-extra';
 import HostedGitInfo from 'hosted-git-info';