VGG models support

This pull request adds the support for the models described in the BMVC-2014 paper "Return of the Devil in the Details: Delving Deep into Convolutional Nets", K. Chatfield, K. Simonyan, A. Vedaldi, A. Zisserman. This comes down to adding a parameter to the LRN layer, denoted as "k" in [Krizhevsky et al., NIPS 2012].

The models have been converted to the current BVLC caffe format and can be accessed from [the Zoo](https://github.com/BVLC/caffe/wiki/Model-Zoo).

~~An important thing to note is that currently the models expect an RGB input, rather than BGR.~~

An example of how to use the models can be found in matlab/caffe/matcaffe_demo_vgg.m