feat(schemas): add support for sprite files for 2.0 and 3.0

refactor schemas to support sprite2 and sprite3 files, while reusing rules in common with sb2 and
sb3 files

BREAKING CHANGE: Change to main API which now takes an additional boolean argument indicating
whether a sprite or project is being validated

lib/parse.js

@@ -8,10 +8,11 @@
  * @return {void}
  */
 module.exports = function (input, callback) {
+    var result;
     try {
-        var result = JSON.parse(input);
-        callback(null, result);
+        result = JSON.parse(input);
     } catch (e) {
         return callback(e.toString());
     }
+    return callback(null, result);
 };