fixed #1811: Adding a method to get file data for JSB. Updating the way of encoding cpp string to jsval or jsval to cpp string.
Merge pull request #2119 from dumganhar/iss1811-getfiledata-jsb

fixed #1811: Adding a method to get file data for JSB. Reverting the implementation of JSStringWrapper.
fixed #1811: Fixing complication error on win32 after this pull request (https://github.com/cocos2d/cocos2d-x/pull/2119).
Merge pull request #2120 from dumganhar/master

fixed #1811: Fixing complication error on win32 after this pull request (https://github.com/cocos2d/cocos2d-x/pull/2119
fixed #1812: A warning of getStringWithEllipsisJni function when compiling it with clang.
Merge branch 'master' of https://github.com/cocos2d/cocos2d-x
fixed #1812: Minor fix.
fixed #1811: getStringWithContentsOfFile ~> getStringFromFile .
Merge pull request #2122 from dumganhar/iss1811

fixed #1811: getStringWithContentsOfFile ~> getStringFromFile .
Merge pull request #2121 from dumganhar/master

fixed #1812: A warning of getStringWithEllipsisJni function when compiling it with clang.