Set reuse address option (fixes #1043)

When the server is killed there may still be client-sockets connected in
the TIME_WAIT state, causing the bind() call to fail. With the
REUSEADDR option we can reuse the address immediately unless another
process is actually *listening* on the same address.
that we want to reuse the address
Verbose name of Assignment inserted, fixed #1036

It is neccessary to refresh the database table for the content types, e. g. by deleting the database and runing syncdb.
Sort requirements, fix #1031.
Add tests according to issue #931.