Re-adds resources in cpp-tests and lua-tests, but removes some large
files. We need to reuse some resources when doing some tests.
Xcode project fix
Removes download-deps.py, using `git submodule update --init` to get the
external libraries. Thanks.
Merge pull request #6571 from dumganhar/re-add-res

'external' folder is a submodule now, re-added resources for cpp-tests and lua-tests except large files
[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #6572 from CocosRobot/update_cocosfiles_1399268435

[AUTO][ci skip]: updating cocos2dx_files.json
Adds submodule for CocoStudio resources (70MB)
Updates xcode project, add ccs-res folder to Resources folder