Fix speed test tool (and possibly others); add script to speedtest imagenet

Was broken due to my #734, sorry guys.  Basically the FilterNet method ignored the current Caffe singleton phase (`Caffe::phase()`) and only looked at the one provided in the `NetState` (e.g. by the solver before initializing, or explicitly in the net proto), so if you used the speedtest tool or any other with a consolidated train/test net expecting it to work correctly because you'd done `Caffe::set_phase(...)`, you were disappointed (though it worked fine with the non-consolidated format).  This fixes that.