Updated install.rst file to cover a fresh install of 0.7.0b3 on Windows using PostgreSQL. Added a new migration file for this fresh install that will add the median function to the PostgreSQL database. Renamed the existing migration file to make it clear that it is to be used when upgrading OpenREM from an earlier version. References issue #257.
@Ed McDonagh, I tried the manage.py createsuperuser before doing the migrate, but I still got errors about certain relationships not existing. The current install doc has a method that works, but it does include a couple of migrate commands that result in errors that may worry some users. There must be a way of doing this cleanly, but I'm not sure what it is.