Hash::Merge::Simple will recursively merge two or more hashes and return
the result as a new hash reference. The merge function will descend and
merge hashes that exist under the same node in both the left and right
hash, but doesn't attempt to combine arrays, objects, scalars, or
anything else. The rightmost hash also takes precedence, replacing
whatever was in the left hash if a conflict occurs. This code was pretty
much taken straight from Catalyst::Utils, and modified to handle more
than 2 hashes at the same time.