Integration of PTP for automated rankings.

*New*:
    + Integration of the [PTP library](https://github.com/owtf/ptp)
    + Automated rankings for several tools (check
    [README](https://github.com/owtf/ptp/blob/master/README.md)
    + Highlight of the automated ranking as such
    + Highlight of the user ranking as such

*FIXME*:

When overriding the current ranking of a plugin's result (such as Skipfish),
the user needs to reload the page in order to see the new ranking.
Might be fixed with some javascript/jquery/something-like-that.