Images do not render in LSTM tutorial

[vrangaswamy]

In https://github.com/dmlc/mxnet-notebooks/blob/master/python/rnn/lstm.ipynb, some of the images that at in the source code and are referenced in the text do not render. Specifically, https://raw.githubusercontent.com/antinucleon/web-data/master/mxnet/notebook/recurrent.jpg and https://raw.githubusercontent.com/antinucleon/web-data/master/mxnet/notebook/unroll.jpg do not render. Both of these links give 404s.