hcard microformat for Twitter Blackbird Pie WordPress plugin

Add an hCard microformat by changing:

<div style="float: left; padding: 0pt; margin: 0pt;"><a style="font-weight: bold;" href="http://twitter.com/intent/user?screen_name=pigsonthewing">@pigsonthewing</a><div style="margin: 0pt; padding-top: 2px;">Andy Mabbett</div></div>

to:

<div style="float: left; padding: 0pt; margin: 0pt;" class="vcard"><a class="nickname url" style="font-weight: bold;" href="http://twitter.com/intent/user?screen_name=pigsonthewing">@pigsonthewing</a><div class="fn" style="margin: 0pt; padding-top: 2px;">Andy Mabbett</div></div>

The additions are:

class="vcard"
class="nickname url"
class="fn"