Merge pull request #20 from conwayb/master

remove inactive users and clients from assigned to filterset
added ticket type field to ticket model and form. added tickettype model and schemigration. added initial data and exposed tickettype and status in admin
Merge pull request #21 from conwayb/feature/ticket_development_type

Add Ticket type (development type) to ticket model.
sort interlaced ticket/todo comments by date on ticket detail view