Tweet text and time parse improvements

Now the tweet text create links from hashtags, mentions, urls.
Added new field that parse the tweet time to get Twitter style "time ago". 

    <ion:tweet field="created_at" />

But I think it would be better if we could use like:

    <ion:tweet:date format="option" />

This way we could format the text with ionize native multilingual **dateformat**, that are "short","medium","long" or "complete", but also mantaining the "time ago" style as default if no format attribute is provided.