Getting Running Locally guide needs work

[AnnaDodson]

The readme only has a brief guide to get up and running and isn't great for beginners. It should also include instructions for getting running on Mac and Windows. Currently only tested on Ubuntu

[beforan]

I've been getting this running on Windows, so I can update the readme with instructions for that

[AnnaDodson]

Would be good to get some instructions for running on a Mac now too