use Class::Load instead of Class::MOP::load_class

as the latter is deprecated
changelog
dzilification
v0.5

 [BUG FIXES]
 - Class::MOP::load_class is deprecated, using Class::Load::load_class
   directly. (Yanick Champoux)

 [STATISTICS]
 - code churn: 7 files changed, 69 insertions(+), 52 deletions(-)