FSAL_HPSS: Complete rework for new FSAL API
FSAL_HPSS: add support for ATTR_[AM]TIME_SERVER
FSAL_HPSS: Set cookie to 0 if not given
FSAL_HPSS: fsal openflags are different from posix ones. HPSS's are the same as posix's, so use fsal2posix for now.