Added the column Volunteer.heard_from and changes
Volunteer.waiver_accepted from boolean to datetime.
Added thawte certificate.
Merge branch 'waiver_date' into david_waiver

Conflicts:
	schemas/crew_management/bulk_data/crew.sql
	schemas/crew_management/bulk_data/first_captains.sql
I have no idea why there are conflicts because I am trying to keep the version from Bill's branch.
added missing var for bwf db.
These have finally been merged. What a farrago!
If all goes well, the waiver work is merged. Needs some actual testing,
though.