update cookie_mgr to use new avhttp utils
Revert "at least gcc 4.4 is now the required compiler!"

This reverts commit 3125c7687120f6ab92ae1fcec57454ac26a231c5.

gcc 4.6 is populer! but boost 1.54 can't be compiled with gcc 4.6.X when
c++11 mode is enabled.