Added tags data to detail template.

To allow for tags to be displayed in the detail template, added the tag library to the front-end model.

Possible use case in detail template:
                {option:tags}
                <h4>Tags</h4>
                <ul>
                    {iteration:tags}
                    <li><a href="{$tags.url}">{$tags.name}</a></li>
                    {/iteration:tags}
                </ul>
                {/option:tags}
Merge pull request #17 from drsdre/patch-2

Added tags data to detail template.