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

ipapython/sysrestore.py

@@ -314,3 +314,14 @@ class StateFile:
         self.save()
 
         return value
+
+    def has_state(self, module):
+        """Return True or False if there is any state stored for @module.
+
+        Can be used to determine if a service is configured.
+        """
+
+        if self.modules.has_key(module):
+            return True
+        else:
+            return False