Use git user name for author name

closes #304

AUTHORS

@@ -13,3 +13,4 @@ Guillermo López-Anglada <guillermo.lopez@outlook.com>
 ntaoo <ntaoo.g@gmail.com>
 Andrés Araujo <a.araujo.azua@gmail.com>
 Kevin Segaud <segaud.kevin@gmail.com>
+sh4869 <nobuk4869@gmail.com>  

lib/src/cli_app.dart

@@ -167,6 +167,14 @@ additional analytics to help us improve Stagehand [y/yes/no]? """);
 
     String author = options['author'];
 
+    if (!options.wasParsed('author')) {
+      try {
+        io.ProcessResult result =
+            io.Process.runSync('git', ['config', 'user.name']);
+        if (result.exitCode == 0) author = result.stdout.trim();
+      } catch (exception) {}
+    }
+
     Map vars = {'author': author};
 
     Future f = generator.generate(projectName, target, additionalVars: vars);