Hard coding concerning the model architecture

[TreeLLi]

There are several places you hard coded the configurations of network architecture in the main program.

They are:

1. The input dimension of Fast-RCNN, which is coded as [4096, ]. But it should be possible to be other numbers, e.g. if i want to use ResNet ended with dimension [1000, ].
2. The spatial_scale of RoiPooling layer, which is coded as 1/16. But in my understanding, this ratio is related to the actual total stride in the convolutional layers.