student.py: fix check for no emails
Run command, build command, and policy are now configurable
Remove debug message
compare: no need for compare to be interactive
Add config.py and simplify configuration handling

 * config.py: loads the cfg object in a single place
 * __init__.py: merges the cfg object into flask's app.config
 * move 'init_db()' from database to initdb
Add test suite
Update .gitignore