Better error when blank database

[dread]

When installing CKAN, when doing "paster serve development.ini", lots of users encounter the error for every request:

ProgrammingError: (ProgrammingError) relation "user" does not exist

This is because the database tables have not been created - they have forgotten or missed the "paster db init" step.

Can we provide a better error to say that the database is not initialised yet?

Implementation options ======================

1. At the start of every request we reflect the database tables and check they are there. This is rather expensive!

2. Uncached requests to the home page start with a cheap database query. If there is an exception then return this error about database setup. I really like Drupal's page for this that has in large letters that the site is currently off-line. Below a line, in small letters, there are developer suggestions on what is wrong and where to look to fix it.