Support for (1) different channel swap, (2) loading mean from binaryproto file (3) loading from image list and siamese image list

[arikpoz]

• Added support for loading networks with any 'channel swap' definition, instead of assuming its (2,1,0) This is done by defining a parameter for "caffe_net_channel_swap" which defaults to (2,1,0) for backwards compatibility.
• Added support for loading mean definition from a .binaryproto file format
• Added support for loading images from an image list or a siamese image list, in addition to the existing loading of images from directory. This is done by adding parameters for setting static files input mode: can be "directory", "image_list" or "siamese_image_list"

[yosinski]

Merged; thanks!