Implement Native Contracts

[eosio]

Implement Native Contracts

[nathanielhourt]

Rewrote issue to reflect that the "system contract" has now been broken up into three different contracts, each responsible for different things, collectively called "the native contracts"

[bytemaster]

I think we can merge all of these into a single "eos" contract that have different scope requirements:

For example, eos::transfer(from,to,amount) only requires scope of from and to where as eos::lock(from,to,amount) requires scope of from, to, and eos.

Under this model we could remove some of the 'notify' handlers and complexity associated with having some logic enforced in 'eos' and other logic enforced in 'system' and still more in 'staked'.

In other words, via scope requirements we can merge all of these into a single contract while still having parallelism.

[heifner]

This is all OBE.