Randomize weights in last layer when fine-tuning
Randomize weights in last layer when fine-tuning

Previously, the last layer's weights were set to zero when fine-tuning.
This works with CrossEntropyCiterion, but may not work with other loss
functions, such as TripletLoss.

See #4

ltrottier/pelu.resnet.torch,ltrottier/pelu.resnet.torch