NewCard: Auto archive email on create

[mrk3767]

I would like to see a checkbox (ticked by default) that will enable the archival of an email when a new card is created.

1. Logic to automatically archive email
2. Checkbox to control whether an email is archived (in create view)
3. Save preference to user's properties

[mrk3767]

When an email is archived, it should probably also be labeled with "Trello"