issue #1683: Updating CCApplication.h/.cpp for linux.
issue #1683: Adding FileUtilsTest.
issue #1683: Updating FileUtilsTest.cpp.
issue #1683: Adding default search path if developer didn't pass it.
issue #1683: Updating CCFileUtils for MAC.
Merge pull request #1904 from dumganhar/iss1683-ccfileutils

issue #1683: Adding FileUtilsTest.Adding default search path if developer didn't pass it.