Build: Dogfood plugin without npm link (#65)

Credit goes to @not-an-aardvark for the recipe:
https://gist.github.com/not-an-aardvark/2358fe2164af521a761710d5f380b1e4

.eslintrc.js

@@ -0,0 +1,31 @@
+"use strict";
+
+var fs = require("fs");
+var path = require("path");
+var PACKAGE_NAME = require("./package").name;
+var SYMLINK_LOCATION = path.join(__dirname, "node_modules", PACKAGE_NAME);
+
+// Symlink node_modules/eslint-plugin-markdown to this directory so that ESLint
+// resolves this plugin name correctly.
+if (!fs.existsSync(SYMLINK_LOCATION)) {
+    fs.symlinkSync(__dirname, SYMLINK_LOCATION);
+}
+
+module.exports = {
+    "root": true,
+
+    "plugins": [
+        PACKAGE_NAME
+    ],
+
+    "env": {
+        "node": true
+    },
+
+    "extends": "eslint",
+
+    "rules": {
+        "strict": "off",
+        "eol-last": "off"
+    }
+};

.travis.yml

@@ -10,6 +10,3 @@ node_js:
 sudo: false
 notifications:
   email: false
-install:
-  - npm link
-  - npm link eslint-plugin-markdown

README.md

@@ -113,8 +113,7 @@ Since code blocks are not files themselves but embedded inside a Markdown docume
 ```sh
 $ git clone https://github.com/eslint/eslint-plugin-markdown.git
 $ cd eslint-plugin-markdown
-$ npm link
-$ npm link eslint-plugin-markdown
+$ npm install
 $ npm test
 ```