installer: Replace boot.iso with installer.iso in .treeinfo as well

Programs like virt-install will look for boot.iso potentially, but we
don't have that, we have an installer.iso.
taskbase: Init repo as archive-z2

We're making a repository to serve via HTTP, not a repo for the local
system.
more systemd: remove RemainAfterExec, enable enable

RemainAfterExit doesn't do what I thought: it just makes
the timer never invoke us again. Remove it.

Add [Install] section to build-monitor; this is what
allows systemctl enable
treecompose: Fix looking for versions in empty repositories

This is kind of a confusing bit about pygobject/introspection - it
gives you a useless "success" boolean that will always be True.
Because if the function fails, it throws an exception.

Ignore the worked value, change the code to check for None in the
first function.

If the commit doesn't exist, let's just throw.