kosu.js: use tsconfig from npm

packages/kosu.js/package.json

@@ -27,6 +27,7 @@
         "@0x/web3-wrapper": "^6.0.5",
         "@babel/core": "^7.4.4",
         "@kosu/system-contracts": "^0.1.0-alpha.4",
+        "@kosu/tsc-config": "^0.1.0",
         "@kosu/tslint-config": "^0.0.4",
         "ethereum-protocol": "^1.0.1",
         "ethereumjs-abi": "^0.6.6",
@@ -60,4 +61,4 @@
     "publishConfig": {
         "access": "public"
     }
-}
+}

packages/kosu.js/tsconfig.json

@@ -1,5 +1,5 @@
 {
-    "extends": "../../tsconfig.json",
+    "extends": "@kosu/tsc-config",
     "compilerOptions": {
         "outDir": "dist",
         "rootDir": "src",