sign PE rpms using the pe:sign_rpms task in the jenkins signing

Because rpms and debs are laid out differently in PE under pkg/ they have a
different sign task to address this. Rather than create a whole extra :jenkins
task for signing PE, we determine which sign task to use based on if we're
building PE

Signed-off-by: Moses Mendoza <moses@puppetlabs.com>
Add tarball to the list of things done in a pe:jenkins:uber_build

We currently don't explicitly build a tarball in the jenkins uber_build for PE
because we haven't shipped sources this way for PE. Now that we're doing this
as part of the workflow for pe-puppet, and it won't hurt anything to do it for
the other projects, we add it to the list of tasks.

Signed-off-by: Moses Mendoza <moses@puppetlabs.com>