Remove HashMaps

From my collection of over 200 local branches with cleanups, for your reviewing pleasure @tdfischer and @jjuran: a removal of the `HashMaps` class which is overengineered and is only used in one place.

Approval-By: @vinniefalco 
Something about having this in hex worries me a bit. I understand the absurdity of this statement, but: Perhaps this should be in base-10 in case the underlying hardware representation changes when rippled is ported to a non-i386 platform and we can rely on the compiler to figure it out.