Remove dependency on pyethereum to improve cross platform support and reduce installation size

[ferret-guy]

Pull in utils and abi from pyethereum in order to allow installation on a wider array of devices fixing the following issues: ConsenSys/ethjsonrpc#19 ConsenSys/ethjsonrpc#5

[maurycyp]

@ferret-guy Mark, are there any licensing issues we should be concerned about with regard to cutting and pasting this code?

[ferret-guy]

The source code is MIT licensed, I have already added the appropriate license headers to the files, but that means that this code conflicts with the unlicense, and would require derivative work to include attribution for thease files.

[maurycyp]

I chose the Unlicense to avoid thinking about these issues. I suppose I could re-license--BSD or MIT may be better.

[ferret-guy]

It seems that most ethereum projects that are MIT, that would mean that in the future if more code needed to be pulled in then, it wouldn't be Unlicense* (except for thease specific files). The other option might be branching pyethereum with a branch for just the utility functions, but that would essentially mean maintaining two parallel packages.