Resolves#106.
This change introduces a new option - `noMarkup`. You could set it the
`setNoMarkup()` method similar to the `setBreaksEnabled()` one.
Example usage:
``` php
<?php
$parsedown = new Parsedown();
$parsedown->setNoMarkup(true);
$parsedown->text('<div><strong>*Some text*</strong></div>');
// Outputs:
// <p><div><strong><em>Some text</em><s;/strong></div></p>
```
You could run the Parsedown testsuite only with:
phpunit --testsuite ParsedownTests
And you could run the Standard Markdown one with:
phpunit --testsuite StandardMarkdown
See more at http://standardmarkdown.com/
