Add append function for String class.

The append function is useful when adding a string.
So, I added it to String class.
issue #2389: Adding cookie support for HttpClient
Support Tizen 2.2 SDK.
- Update project files.
- based on develop branch.
- HelloCpp, SimpleGame, HelloLua, TestLua available to build.
issue #2300: A fix of missing invoking 'initXXX' in clone method.(FadeOut, DelayTime).
'tile' --> 'getTile', 'orignalTile' --> 'getOrignalTile'
Merge pull request #3123 from pyrasis/tizen_2.2

Support Tizen 2.2 SDK
closed issue #2386 : Fix bug : add a new method to clear the stencil buffer bit used by ClippingNode
Update .travis.yml
enableCookies is static method now
Merge pull request #3124 from dumganhar/rename-method

issue #2300: A fix of missing invoking 'initXXX' in clone method.(FadeOut, DelayTime).
Merge pull request #3125 from dabingnn/Iss2386-ClippingNode-AsChild-Bug

closed issue #2386 : ClippingNode works wrongly when being set as a child
Merge pull request #3121 from tks2shimizu/develop

Add append function for String class.
[ci skip]
re adds copy() as a deprecated method

...in order to make easier the port to v3.0
Merge pull request #3128 from ricardoquesada/copy_deprecated

re adds copy() as a deprecated method
Merge pull request #3122 from dumganhar/iss2389-http-cookie

closed 2389: Adding cookie support for HttpClient
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-x into ScriptHandler