Make API and web roll back any open transactions on timeout

Make API and web roll back any open transactions on timeout

By default the exception thrown by Timeout::timeout is caught
using Kernel::catch so that it cannot be stopped by intermediate
exception handlers. The problem with that is that it stops any
database transactions that were in progress being rolled back
because they never see the exception.

Fortunately passing a class to Timeout::timeout changes it's
behaviour so that the exception is thrown and caught in the normal
way, allowing the database transactions to rollback.