when adding a repo with fingerprint, make sure to store the pubkey
The logic here is crufty, so I slapped a flag in there to make sure that
the pubkey gets stored when someone configures a repo and includes the
fingerprint. When the fingerprint is set, it will first download the
index.jar and verify it against that fingerprint. The logic for storing
the pubkey permanently happens later in the XML parsing, so there needs to
be a flag to signal to store the pubkey in this case.
Before the flow was always index.xml -> get pubkey -> index.jar. Really,
there should no longer be support for unsigned repos, then all of this
stuff can be dramatically simplified.