Commiting a version of the multi-phase snoop atomic bus so people can see the framewo...

Commiting a version of the multi-phase snoop atomic bus so people can see the framework.  Doesn't work, but also doesn't break uni-processor systems.
Working on pulling out the changes in the cache so that it remains working.

src/mem/bus.cc:
    Changes for multi-phase snoop
    Some code for registering snoop ranges (a version that compiles and runs, but does nothing)
src/mem/bus.hh:
    Changes for multi-phase snoop
src/mem/packet.hh:
    Flag for multi-phase snoop
src/mem/port.hh:
    Status for multi-phase snoop

--HG--
extra : convert_revision : 4c2e5263bba16e3bcf03aabe36ff45ec36de4720