fabfile: fix write_app_yaml()
fabfile: dev: use --show_mail_body
Multi-incident organizations: incident -> incidents

Includes auto-migration, changes to admin, and changes to
authentication.
Multi-incident orgs: check legacy incident field at auth
Remove errant pdb tracepoints
Multi-incident orgs: send templated email when org joins another incident
Multi-incident orgs: hide local as well as global admins as existing orgs
Multi-incident orgs: add linebreak to email_templates/organization_joins_incident.body.txt
key: add comment
CheckAuthorization: check org may access event
On init, add default contact for admin org
Organization.may_access(): allow global admin always
Restrict downloads by orgs' incidents

Includes refactoring out of download handlers.
Merge branch 'multi-incident-orgs'

Conflicts:
	sandy-disaster-recovery/admin_handler/admin_edit_organization_handler.py
	sandy-disaster-recovery/export_bulk_handler.py
	sandy-disaster-recovery/key.py
	sandy-disaster-recovery/organization.py
CheckAuthorization(): lookup org from db, not cache