Previously, the pe_install task would ignore any erroneous exit codes
emitted by the pe installer. This caused user confusion because actual
failures to install resulted in strange errors later in the plan. This
commit improves the user experience by ensuring some basic smoke tests
pass, or else actually failing at this step.

It can be done at the same time other agents are installing

When signing CSRs, it is common that the CSR will have been submitted
just prior. Previously, plans which did both would have to pause after
submitting the CSR to ensure there was time for the server to have fully
processed it before running the sign task, in order to avoid any chance
of ready-to-sign timing problems.

This commit makes the sign_csr task itself attempt to sign up to six
times, waiting one second between attempts, in order to avoid needing to
do that in the plan.

The default PE version, the listed supported Bolt version