updates fileutiles.walk to use glob

tested with python 2.6 and 2.7, glob appears way back in 2.3, but i don't know what version of python htools is targeting (presumably whatever robofont uses?)

(also, apologies for these softball pull reqs, i'm trying to get up to speed on robofont scripting this weekend and just started diving into htools since it seems fairly comprehensive. additionally, if there _is_ some part of htools you'd like help with, i'm happy to help out any way i can)