title: typescript compiler (tsc) command not working with tsconfig
body: <p>I installed typescript globally ( <code>npm install typescript -g</code> )</p>
  
  <p>Then created a folder, ran  <code>npm --init</code>, then <code>npm intall typescript --save-dev</code> - it installed typescript@2.1.4</p>
  
  <p>In the folder , I create 'helloworld.ts`</p>
  
  <pre><code>var msg = 'Hello World';
  console.log (msg);
  </code></pre>
  
  <p>ran tsc command with file option - <code>tsc helloworld.ts</code> and see it compiled to <code>helloworld.js</code>.</p>
  
  <p>Next, I want to use tsconfig.json, so I run <code>tsc --init</code> - this doesn't work, says <code>Unknown option 'init'</code></p>
  
  <p>i say alright, let me try adding tsconfig.json manually and add it in the folder root as below: </p>
  
  <pre><code>{
      "compilerOptions": {
          "target": "es5"
      },
      "files": [
          "helloworld.ts"
      ]
  }
  </code></pre>
  
  <p>and I run <code>tsc</code> on command prompt, but it won't work and outputs me the syntax, example and options of how to use tsc <code>Syntax:   tsc [options] [file]  ...</code></p>
  
  <p>whats wrong? </p>
  
  <p><code>where tsc</code> gives below:</p>
  
  <pre><code>C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.0\tsc.exe
  C:\Program Files (x86)\Microsoft SDKs\TypeScript\1.0\tsc.js
  C:\Users\Kap\AppData\Roaming\npm\tsc
  C:\Users\Kap\AppData\Roaming\npm\tsc.cmd
  </code></pre>