Added builder for inbox and forwardings.
Added task2sqltask testing helper.
Reworked the inbox tabs.
Added closed-forwardings tab used on yearfolders.
Added new state refused to the forwarding workflow.
Added refuse-task form, including storing a copy functionality.
Marked refused forwarding as pendet in tasklistings.
Reworked the AssignTaskForm and add tests to make it easier to customize.
Added assign inbox form for the reassign-refused transition.
Pep8 and pyflakes cleanup and updated translations