Decommission of TurboGears 1.5 and friends

This package branch is no more developed/supported upstream since about 2011.
There is devel/py-turbogears2 (current stable and supported branch) in ports
tree. Since there are no ports, depending on that, mark them deprecated and
set to expire at 2017-03-03

Discussed with: nivit, wen (maintainers, by mail)