Some restructuring of scripts and settings

The motivation behind this is threefold:

* I was not very happy with the project structure and mixed location of scripts and settings. I've tried to put all scripts and settings in the `scripts` and `config` directories.
* I do not like the fact of having files that do not live under version control and I am moving away from that pattern as much as possible in my current django projects. In particular this applies to `local_settings`. I am now only keeping personal secrets out of the way (and ideally we should put these in environment vars).
* I am now running deploystream for personal stuff and already sharing it with people in the office, and I found it a pain to manage the two different sets of repos (when we discuss settings in proper detail, we may want to introduce the concept of "contexts")

Now you can add your own settings in `config` too, e.g. `config/local_settings_alex.py` etc. In order to run:

```
CONFIG=alex ./scripts/runserver.sh
```