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.