(work in progress) Inception Model

fixes #82
 * [x] nn.DepthConcat
 * [x] constructor
 * [x] maxnorm
 * [x] nOutputFrame
 * [x] unit test
 * [x] reset
 * [x] example script using SVHN 
 * [x] harmonize Convolution2D
 * [x] can we sparse initialize a reduction layer? Yes
 * [x] modify nn.SpatialMaxPooling such that strides need not equal kernel sizes ( see [cunn PR](https://github.com/torch/cunn/pull/30))