A new demo runner.

Adds a demo runner written in Python.

I believe this version is more readable and maintainable. It also makes it a little more flexible to run it on a local machine. The way the datasets are organized within the `data` directory is also a slightly different. If we request for the `enron` dataset for example, we'll import all files that match the pattern `*.bin*` within the `data/enron` directory.

The default setup hierarchy is same as before so AWS box doesn't need to be changed.
```
orly/
    demo.py
    bin/
    data/
    packages/
    webui/
```

and run `./demo.py {dataset}`

If there are local configurations, however, you can provide them via the command line arguments. Like so: `./demo.py {dataset} --webui-dir=/home/mpark/OrlyAtomics/webui --mem-sim-mb=512`.

You could also save the config in a file. In `demo.local` (or whatever) with contents:
```
--web-dir=/home/mpark/OrlyAtomics/webui
--mem-sim-mb=512
```
Then run ``./demo.py {dataset} `< demo.local` ``
nit-pick: signal comes before subprocess alphabetically