Update greeter.ts formtting

Add spacing in a StyleCop like fashion, and consolidate the var statements by eliminating the variable "str"

Author: DecimusN7

greeter/greeter.ts

@@ -4,6 +4,7 @@ class Greeter {
         return "<h1>" + this.greeting + "</h1>";
     }
 };
+
 var greeter = new Greeter("Hello, world!");
-var str = greeter.greet();
-document.body.innerHTML = str;
+    
+document.body.innerHTML = greeter.greet();