Implement an installer for the Dogtag certificate system.

The CA is currently not automatically installed. You have to pass in the
--ca flag to install it.

What works:
- installation
- unistallation
- cert/ra plugins can issue and retrieve server certs

What doesn't work:
- self-signed CA is still created and issues Apache and DS certs
- dogtag and python-nss not in rpm requires
- requires that CS be in the "pre" install state from pkicreate

ipaserver/plugins/ra.py

@@ -55,7 +55,10 @@ class ra(Backend):
     Request Authority backend plugin.
     """
     def __init__(self):
-        self.sec_dir = api.env.dot_ipa + os.sep + 'alias'
+        if api.env.home:
+            self.sec_dir = api.env.dot_ipa + os.sep + 'alias'
+        else:
+            self.sec_dir = "/etc/ipa/ra" + os.sep + 'alias'
         self.pwd_file = self.sec_dir + os.sep + '.pwd'
         self.noise_file = self.sec_dir + os.sep + '.noise'
         self.ipa_key_size = "2048"