Add request tokens to session, for mitigating CSRF
Added functionality to validate requests.
Which aims to help mitigate CSRF attackks.

Sessions have a requestToken - 32 random bytes.  This token can be
used to validate that a request has not been forged.

A route can be annotated with:

    @RequireValidRequestToken()
    @RequireValidRequestToken(@Param("name"))
and
    @RequireValidRequestPathToken()
    @RequireValidRequestPathToken(@Param("name"))

In a form, the following components can be used:

    <request-token />
    <request-token id="name"/>

and

    <request-path-token path="/path"/>
    <request-path-token path="/path" id="name"/>

The following EL functions are exposed:

    request_token()

and

    request_path_token('/path')