GitHub resolver should move contents when extracting.

lib/core/resolvers/GitHubResolver.js

@@ -77,9 +77,7 @@ GitHubResolver.prototype._checkout = function () {
             to: that._tempDir
         });
 
-        extract(file, that._tempDir, {
-            keepStructure: true      // Keep the folder structure as it is!
-        })
+        extract(file, that._tempDir)
         .then(deferred.resolve, deferred.reject);
     });