Add eslint with exponent config

Same config as the universe repo minus the exp plugin.

Closes #82

fbshipit-source-id: a040864

.eslintignore

@@ -0,0 +1 @@
+node_modules

.eslintrc

@@ -0,0 +1,11 @@
+{
+  "extends": "exponent/react",
+  "plugins": [
+    "flow-vars"
+  ],
+  "rules": {
+    "react/no-comment-textnodes": 0,
+    "flow-vars/define-flow-type": 1,
+    "flow-vars/use-flow-type": 1
+  }
+}

package.json

@@ -4,6 +4,7 @@
   "description": "Route-centric navigation libary for React Native.",
   "main": "./src/ExNavigation.js",
   "scripts": {
+    "lint": "eslint ./src ./example",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "repository": "https://github.com/exponentjs/ex-navigation.git",
@@ -42,6 +43,12 @@
     "warning": "^2.1.0"
   },
   "devDependencies": {
+    "babel-eslint": "^6.1.0",
+    "eslint": "^3.0.0",
+    "eslint-config-exponent": "^2.0.2",
+    "eslint-plugin-babel": "^3.3.0",
+    "eslint-plugin-flow-vars": "^0.4.0",
+    "eslint-plugin-react": "^5.2.2",
     "flow-bin": "^0.29.0",
     "react": "~15.2.1",
     "react-native": "github:exponentjs/react-native#sdk-8.0.0"