Add `--force-schema-create` switch in server run script
Add `--force-schema-create` switch in server run script

This helps me because I develop model changes often in accordance to
unit tests, which only target the testing database, and tear
everything down at the end.
This way, I only have to issue a `http --force-schema-create` followed by
an `alembic upgrade` and no further psql fiddling is required.

agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft