[perl #44607] [CAGE] Hoist slurp_file() into Parrot::Util

[James Keenan via RT]

Andy had filed 44607 this morning, but for some reason it didn't show up in my 
newsreader 
until after I had filed 44615.  So whoever wants to work on 
Parrot::YetToBeNamed should write 
Parrot::Util instead.