Move generated contract wrappers and artifacts into contracts package

packages/contracts/.solhintignore

@@ -0,0 +1,3 @@
+contracts/tokens/ZRXToken/ERC20Token_v1.sol
+contracts/tokens/ZRXToken/Token_v1.sol
+contracts/tokens/ZRXToken/UnlimitedAllowanceToken_v1.sol

packages/contracts/compiler.json

@@ -1,6 +1,6 @@
 {
-    "artifactsDir": "../migrations/artifacts/development",
-    "contractsDir": "src/",
+    "artifactsDir": "./generated-artifacts",
+    "contractsDir": "./contracts",
     "compilerSettings": {
         "optimizer": {
             "enabled": true,
@@ -50,7 +50,6 @@
         "TestExchangeInternals",
         "TestSignatureValidator",
         "TestStaticCallReceiver",
-        "TokenRegistry",
         "Validator",
         "Wallet",
         "WETH9",

packages/contracts/contracts/tokens/ZRXToken/ERC20Token_v1.sol

@@ -1,6 +1,6 @@
 pragma solidity ^0.4.11;
 
-import { Token_v1 as Token } from "../Token/Token_v1.sol";
+import { Token_v1 as Token } from "./Token_v1.sol";
 
 contract ERC20Token_v1 is Token {
 

packages/contracts/contracts/tokens/ZRXToken/UnlimitedAllowanceToken_v1.sol

@@ -18,7 +18,7 @@
 
 pragma solidity ^0.4.11;
 
-import { ERC20Token_v1 as ERC20Token } from "../ERC20Token/ERC20Token_v1.sol";
+import { ERC20Token_v1 as ERC20Token } from "./ERC20Token_v1.sol";
 
 contract UnlimitedAllowanceToken_v1 is ERC20Token {
 

packages/contracts/contracts/tokens/ZRXToken/ZRXToken.sol

@@ -19,7 +19,7 @@
 pragma solidity 0.4.11;
 
 // solhint-disable-next-line max-line-length
-import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "../../../1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol";
+import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "./UnlimitedAllowanceToken_v1.sol";
 
 
 contract ZRXToken is