Updates download-deps.py to support download several files.
Adds config.json for runtime
Updates .gitignore.
[AUTO][ci skip]: updating cocos2dx_files.json
Updates download-deps.py
Null ptr check in value assignment
[Jenkins][ci skip] Add lua-runtime-bin to support pull request build
Merge pull request #6684 from CocosRobot/update_cocosfiles_1399888755

[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #6687 from dumganhar/value-fix

Null ptr check in value assignment
Merge pull request #6686 from dumganhar/download-runtime

Updates download-deps.py to support  to download several zip files. (external and lua-runtime-bin)
Merge pull request #6688 from lmskater/add-lua-runtime-bin

[Jenkins][ci skip] Add lua-runtime-bin to support pull request build