fix(challenge): Format challengeSeed to encourage best practices.

* By re-formatting the seed a bit, I hope to help campers complete
their object definitions before they instantiate anything from them.

challenges/02-javascript-algorithms-and-data-structures/object-oriented-programming.json

@@ -346,11 +346,10 @@
         "  this.name = name;",
         "}",
         "",
-        "let beagle = new Dog(\"Snoopy\");",
-        "// Add your code below this line",
         "",
         "",
-        ""
+        "// Add your code above this line",
+        "let beagle = new Dog(\"Snoopy\");"
       ],
       "tests": [
         "assert(beagle.numLegs !== undefined, 'message: <code>beagle</code> should have a <code>numLegs</code> property.');",