title: angular-material change checkbox color
body: <p>I'm using checkbox of angular-material2. Currently the default color of checkbox is coming as purple color.<br>
  Looks like they have changed default color of checkbox from "primary" to accent.<br>
  Is there a way to get "primary"(green) color instead of purple without overriding css.<br>
  I tried giving color="primary" to  but that didn't worked. </p>
  
  <p>Code : <code>&lt;md-checkbox&gt;&lt;/md-checkbox&gt;</code>   </p>
  
  <p>Import statement: </p>
  
  <pre><code>import {MdCheckbox} from '@angular2-material/checkbox';
  </code></pre>
  
  <p>Plunker <a href="http://plnkr.co/edit/sFC0kfdzj7fxtUC3GXdr?p=preview" rel="noreferrer">http://plnkr.co/edit/sFC0kfdzj7fxtUC3GXdr?p=preview</a></p>