Disable /admin/ endpoint

[toolness]

As mentioned in #59 (comment), the /admin/ endpoint isn't documented.

Upon further investigation, it appears this endpoint is actually provided by sandman2, and exposes a Flask-Admin blueprint that allows users to view and edit table data.

The endpoint is protected by basic auth, whose username and password are determined by the AUTOAPI_ADMIN_USERNAME and AUTOAPI_ADMIN_PASSWORD environment variables, respectively.

Here's an example dataset in the admin view:

One question I have is in regards to editing the data. It seems like the database is constantly flushed and re-built from CSV data, so I assume that any edits will be wiped away when the CSVs are re-imported?

[toolness]

Talked to @gbinal last week and it looks like we might actually just want to disable this endpoint entirely, particularly given the potential confusion/loss of data caused by editing via the admin UI and then importing a CSV later.