Remove constructor pattern

[tarrencev]

This removes the use of the constructor pattern since there is no need to instantiate a library of pure functions. Makes for a much cleaner interface imo.

@axic

[axic]

Thank you. Initially the API was meant to be similar to web3.js in the sense of parsing an ABI JSON description would lead to an object with function calls, hence the constructor based code.

I don't think we'll end up that way, so probably I'll merge this.

We also started a discussion on the API here: #2

[tarrencev]

Cool, sounds good. Would be happy to contribute!

[axic]

@tarrencev do you want to rebase this?

I do like the following better though:

var ABI = {}

ABI.rawEncode = 
...

module.exports = ABI;

[tarrencev]

@axic sure no problem