def url_for(method,params={},endpoint='rest')
      params['api_key'] = @api_key
      params['method'] = method if method
      signature = sign(params)
      url = BASE_URL + endpoint + '/' + params_to_url(params.merge({'api_sig' => signature}))
      url
    end
def url_for(method,params={},endpoint='rest')
      params['api_key'] = @api_key
      params['method'] = method if method
      signature = sign(params)
      url = BASE_URL + endpoint + '/' + params_to_url(params.merge({'api_sig' => signature}))
      url
    end
Get the url for a particular call, doing the signing and all that other stuff.

 [method] the RTM method to call
 [params] hash of parameters.  The +method+, +api_key+, and +api_sig+ parameters should _not_ be included.
 [endpoint] the endpoint relate to BASE_URL at which this request should be made.