Add tripleo-puppet-elements to pull-tools
Add tripleo-puppet-elements to pull-tools

Now that we're using puppet elements with TripleO, it will be useful if
pull-tools can keep it up to date for us.

Change-Id: Iee97b1b0d0c6fdcee0e19dcf5910d4446ffcdb9f

rdo-management/tripleo,rdo-management/tripleo