Fix ipa-server-install in pure IPv6 environment

Installation in pure IPv6 environment failed because pki-tomcat tried to use
IPv4 loopback. Configuring tomcat to use IPv6 loopback instead of IPv4 fixes
this issue.

https://fedorahosted.org/freeipa/ticket/4291

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipaserver/install/cainstance.py

@@ -578,6 +578,10 @@ class CAInstance(DogtagInstance):
             config.set("CA", "pki_external_ca_cert_chain_path", cert_chain_file.name)
             config.set("CA", "pki_external_step_two", "True")
 
+        # PKI IPv6 Configuration
+        config.add_section("Tomcat")
+        config.set("Tomcat", "pki_ajp_host", "::1")
+
         # Generate configuration file
         with open(cfg_file, "wb") as f:
             config.write(f)