Ability to save/retrieve CCData into/from CCUserDefault

I needed to save some binary data into CCUserDefault object... so I created this patch.
It basically moves CCData.* files from extensions/CCBReader into cocos2dx/cocoa and add some extra methods to CCUserDefault class.

The binary data is stored as base64 encoded string (added encoding function into cocos2dx/support/base64.cpp

I think that other developers might find this useful and you add it to the project... 
I hope that I didn't miss any build script/project... and platforms i'm not familiar will still build  without errors.

Regards
Jaro