Simplifying the install process for new developers and making it easier to work with local directories

The main content of this pull request is a move to use a requirements.txt file which allows you to run this command:

```pip install -r requirements.txt```

To install all the dependency packages in one shot. It's also recommended to run the ```pip freeze``` command which will snapshot all the versions used, which can then be put into the requirements.txt file to ensure that people are all running the same versions of the packages.

The other change is to ```database_example.py``` to make it easier to work with local directories, rather than setting up directories in /var.