Make the project contents a little bit more attractive

[jgonggrijp]

This pull request combines a couple of small edits that should help to improve the appeal of our project a little. Most importantly I added a note to the Readme to repeat that anyone who wants to contribute is welcome, ordered the Dependencies by importance, and replaced the suggestiions in setup.py to restart or logoff/login by useful instructions on how to refresh the environment variables.

I still need to check that the command displayed to Windows users is correct.

[sleepingdrone]

I tested the command on windows and it works, but I don't think it's very user friendly to execute since I can't copy and paste it due to line wrap and the way select and copy work in the Windows commandline.

We're done! Now all you need to do is run these commands:

  for /f "tokens=3* skip=2" %i in ('reg query "HKCU\Environment" /v RED_SPIDER_R
OOT') do (set RED_SPIDER_ROOT=%i)
  rsshell

[jgonggrijp]

Thanks for testing. I seem to recall I also walked into some other issue with that command when I tested it myself. Back to the drawing table!