Runs through our list of filters provided by the configuration
object to get them ready for use, including getting uri masks
to proper regex, removing those we can from the possibilities
based on HTTP method, etc.

The resulting $this->filters is an array of only filters
that should be applied to this request.

We go ahead an process the entire tree because we'll need to
run through both a before and after and don't want to double
process the rows.

@param string $uri

@return Filters