Status of notes created by importer

[tbar0970]

There is a system-wide setting "default status for new notes". I've got it set to "action required" because when we create a new note it's usually for somehting that needs doing.

But this default value is also being applied to notes created by the importer, which in this case isn't what I want.

Options:

1. Warn the user that the default status will be used. They can go and change the default temporarily if they want.
2. Allow a "note status" setting in the importer settings.
3. Always use "no action required" for importer notes.
4. Allow a "note_status" column in the import data

Related: #749

[tbar0970]

I'm labelling this as both a FR and a bug. Because the current behaviour is technically correct but I think it's quite problematic.