Found and fixed 3 decoder.isa bugs!!! Now the hello_world program runs for a while

Found and fixed 3 decoder.isa bugs!!! Now the hello_world program runs for a while
before getting in a infinite loop. It actually "tries" to syscall too, but syscalls
aren't implemented just yet

arch/mips/faults.cc:
    more descriptive names for faults (will help future users as well as me!)
arch/mips/isa/base.isa:
    make sure we are printing out "BasicOp" format disassembly instructions as dest,src,src instead of src,src,dest
arch/mips/isa/decoder.isa:
    FIX LW/SW Bug!!!! I was actually loading a byte instead of a word
    FIX JALR Bug!!!! I was not saving the link address in R31 for this instruction
    FIX SLL/NOP Bug!!! We now recognize the varying flavors of sll,nop,ehb,& ssnop correctly
base/loader/elf_object.cc:
    change back to original way
base/loader/elf_object.hh:
    change back to original!

--HG--
extra : convert_revision : 39b65fba31c1842ac6966346fe8a35816a4231fa