Make the installer/uninstaller more aware of its state

We have had a state file for quite some time that is used to return
the system to its pre-install state. We can use that to determine what
has been configured.

This patch:
- uses the state file to determine if dogtag was installed
- prevents someone from trying to re-install an installed server
- displays some output when uninstalling
- re-arranges the ipa_kpasswd installation so the state is properly saved
- removes pkiuser if it was added by the installer
- fetches and installs the CA on both masters and clients

ipaserver/install/bindinstance.py

@@ -377,6 +377,9 @@ class BindInstance(service.Service):
         resolv_fd.close()
 
     def uninstall(self):
+        if self.is_configured():
+            self.print_msg("Unconfiguring %s" % self.service_name)
+
         running = self.restore_state("running")
         enabled = self.restore_state("enabled")