Fix opensocial tasks and processes presentation

There are several problems:

• whenever a document referenced by a task/process is not here, no tasks or processes are returned
• there is a lot of missing information on a task, compared to the old dashboard (task name, directive, comment, start date)
• information for a process is inconsistent: it should present the process name, title of the document and creation date (instead of directive and due date that will never be filled)
• useless pagination links are presented but there is no pagination