Module 'torch-rnn' not found

Hi,

Newbie here. I'm trying to get densecap running on the pre-trained model but my system can't seem to locate the torch-rnn module. I suspect something's up with the pathways.

I run:

`th run_model.lua -input_image imgs/elephant.jpg -gpu -1`

This is the error I'm getting:

```
/Users/rebeccaricks/torch/install/bin/luajit: .../rebeccaricks/torch/install/share/lua/5.1/trepl/init.lua:389: .../rebeccaricks/torch/install/share/lua/5.1/trepl/init.lua:389: .../rebeccaricks/torch/install/share/lua/5.1/trepl/init.lua:389: module 'torch-rnn' not found:No LuaRocks module found for torch-rnn
no field package.preload['torch-rnn']
no file '/Users/rebeccaricks/.luarocks/share/lua/5.1/torch-rnn.lua'
no file '/Users/rebeccaricks/.luarocks/share/lua/5.1/torch-rnn/init.lua'
no file '/Users/rebeccaricks/torch/install/share/lua/5.1/torch-rnn.lua'
no file '/Users/rebeccaricks/torch/install/share/lua/5.1/torch-rnn/init.lua'
no file './torch-rnn.lua'
no file '/Users/rebeccaricks/torch/install/share/luajit-2.1.0-beta1/torch-rnn.lua'
no file '/usr/local/share/lua/5.1/torch-rnn.lua'
no file '/usr/local/share/lua/5.1/torch-rnn/init.lua'
no file '/Users/rebeccaricks/.luarocks/lib/lua/5.1/torch-rnn.so'
no file '/Users/rebeccaricks/torch/install/lib/lua/5.1/torch-rnn.so'
no file '/Users/rebeccaricks/torch/install/lib/torch-rnn.dylib'
no file './torch-rnn.so'
no file '/usr/local/lib/lua/5.1/torch-rnn.so'
no file '/usr/local/lib/lua/5.1/loadall.so'
stack traceback:
[C]: in function 'error'
.../rebeccaricks/torch/install/share/lua/5.1/trepl/init.lua:389: in function 'require'
run_model.lua:5: in main chunk
[C]: in function 'dofile'
...icks/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:150: in main chunk
[C]: at 0x0108d59cf0
```