Fixes to cache eliminating the assumption that the Packet is still valid after sendin...

Fixes to cache eliminating the assumption that the Packet is still valid after sending out a request.
Still need to rework upgrades into this system, but works for now.

src/mem/cache/base_cache.cc:
    Re order code to be more readable
src/mem/cache/base_cache.hh:
    Be sure to delete the copy on a bus block
src/mem/cache/cache_impl.hh:
    Be sure to remove the copy on a writeback success
src/mem/cache/miss/mshr_queue.cc:
    Demorgans to make it easier to understand
src/mem/tport.cc:
    Delete writebacks

--HG--
extra : convert_revision : 9519fb37b46ead781d340de29bb342a322a6a92e