Collective.task

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- Removed useless atct config.
[sgeulette]
- Changed `task description` translation
[sgeulette]

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- Removed bad step containing empty dependency (persisted now).
[sgeulette]
- Set allowed_mime_types on task_description
[sgeulette]

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- Removed bad step containing empty dependency.
[sgeulette]

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- Added batch actions (collective.eeafaceted.batchactions) to change assigned group or assigned user.
[sgeulette]

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- Corrected bug when a parent field is multivalued.
[sgeulette]

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- Use imio.prettylink column for title if imio.prettylink product is present.
[sgeulette]