Settings and dependabot fixes

[dchiller]

This PR addresses two minor issues:

1. Fixes an issue in how the "DEVELOPMENT" environment variable was read in the django settings.py file. The result of the os.environ.get call is alway a string, so we need to check it against a string in order to get a boolean value.
2. It has dependabot check for updates monthly rather than weekly. Since we look for patch updates, this was resulting in a lot of dependabot PR's being opened and then closed much more frequently than we actually update our servers.

It also removes an unused version parameter in the docker-compose.yml file.