fix(local-cli): if _gitignore exists, rename it to .gitignore

Because npm never publishes a `.gitignore` file, we need to rename
our `.gitignore` files in our templates to `_gitignore` and have the
`hops-local-cli` `init()` method rename it again, after unpacking.

Read more about it: npm/npm#1862

Related to: #275

packages/local-cli/init.js

@@ -78,6 +78,12 @@ function init (root, appName, options) {
       strip: 1
     }).then(function () {
       fs.unlinkSync(tarball);
+      if (fs.existsSync(path.resolve(appRoot, '_gitignore'))) {
+        fs.renameSync(
+          path.resolve(appRoot, '_gitignore'),
+          path.resolve(appRoot, '.gitignore')
+        );
+      }
       var newPackageManifest = readPackageManifest(pathToPackageManifest);
       writePackageManifest(
         pathToPackageManifest,