Migrate to 16.04

All images should move from Ubuntu 14.04 LTS to 16.04 LTS, except for CUDA images where versions <= 7.5 should remain with 14.04 and versions >= 8.0 should migrate (see https://github.com/NVIDIA/nvidia-docker/issues/110).
- [ ] **brainstorm**
- [ ] **caffe**
- [ ] **cuda-brainstorm**
- [ ] **cuda-caffe**
- [ ] **cuda-digits**
- [ ] **cuda-keras**
- [ ] **cuda-lasagne**
- [ ] **cuda-mxnet**
- [ ] **cuda-neon**
- [ ] **cuda-pylearn2**
- [ ] **cuda-ssh**
- [ ] **cuda-theano**
- [ ] **cuda-torch**
- [ ] **cuda-vnc**
- [ ] **digits**
- [ ] **fglab**
- [ ] **fgmachine**
- [ ] **keras**
- [ ] **lasagne**
- [ ] **localtunnel**
- [ ] **mxnet**
- [ ] **neon**
- [ ] **neuron** (LXTerminal not working)
- [ ] **pylearn2**
- [x] **ros**
- [x] **samba**
- [x] **spearmint**
- [x] **ssh**
- [x] **sshx**
- [ ] **theano**
- [ ] **torch**
- [ ] **vnc** (LXTerminal not working)
- [ ] **vnc-ros** (LXTerminal not working)