add nonce functions to Block; add lodash 2.4.1

lodash helps check nonce equality, and has other utilities
that have been helpful from experience
update genesis and acct structure per pyethereum 456c64baa0de572269f8ebfa879e2d6fa2f1f443

update tests submodule per pyethereum b8d83700d2187f3f399a85bd1f807e00e75096e9
fix genesis alloc
validate that replaying tx throws InvalidNonce
test genesis hash