Create task admin to cater for failed tasks

[cdausmus]

A few times, tasks have failed to upload due to one issue or another (e.g. incorrect file format) and the upload queue gets stuck but there's no way to see this or what is wrong.

Add a task admin that displays all current tasks pending for upload and flag any errors that may have occurred (will need to record error/stacktrace).
Provide ability to reset/delete pending uploads.
Provide ability to reset project (i.e. delete all pending tasks to prevent having to clone and start again)
Notification to digivol email/institution if upload errors have occurred (at end of list after all retries)