Refactored core

This is the plugin refactored from the ground up. It fleshes out a series of resource-specific objects to allow you to do each of the main functions. Not every method call is there but most are there and more are on the way.

This implementation *is* completely backwards compatible with the previous implementation. The only change required is including the new path as shown here:
https://github.com/caseysoftware/fullcontact-api-php/commit/e0e1d625eeee0634397bc2a9d87188c272c16157

This also includes unit tests.. which don't currently use mock objects/requests so if someone uses the tests indiscriminately, they can drain their account credit. Which I have done.