projects: consolidate and refactor project archive code

projects: consolidate and refactor project archive code

Create a new archive_and_delete method on the Project
class that contains the original logic from delproj.cgi
which is capable of handling multiple deletions of
same-named projects.

Replace the delproj.cgi logic with a call to the new
function.

Replace the inferior logic in trash-project.pl with a
call to the new function.  As a result, trash-project.pl
can now handle multiple deletions of same-named projects.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>