Security-related variables using hardcoded defaults

[fmigneault]

The fact that they're hardcoded at all is a problem though. Because even without the changes you've made here, we could still override MAGPIE_ADMIN_USERNAME and then the JUPYTERHUB_ADMIN_USERS would no longer match.

Why don't we make an issue for this and we'll fix it in a later PR

Originally posted by @mishaschwartz in #415 (comment)

birdhouse-deploy/birdhouse/env.local.example

Line 27 in 10128e5

export JUPYTERHUB_ADMIN_USERS="{'admin'}" # python set syntax

The above variable should use the expected reference to MAGPIE_ADMIN_USERNAME.
Other locations using similar configurations must be adjusted and validated.

[mishaschwartz]

Note for later:

• we should also raise a warning if the ALLOW_UNSECURE_HTTP variable is set to True (it should not be set to True in a production environment so we should warn the user)