Add reverse DNS record when forward is created

Adding reverse DNS record may be a time consuming task, especially
for IPv6 addresses. Having a way to automatically create a reverse
record when a forward record is created could speed up the process.
host-add command already has this possibility.

This patch takes advantage of the new per-type API and adds new
options for A/AAAA record types: --a-create-reverse and
--aaaa-create-reverse. These commands can be used to automatically
create reverse records for new A/AAAA addresses (both forward
and reverse zones need to be managed by FreeIPA server):

ipa dnsrecord-add example.com foo --a-rec=10.0.0.1 --a-create-reverse

This command would add a new A record to record foo in zone
example.com and a PTR record to appropriate reverse zone for
IP address 10.0.0.1 (for example PTR record 1 in zone
0.0.10.in-addr.arpa. pointing to foo.example.com.).

Few modification were done to new DNS API to support this feature:
 - Refactor --ip-address option handling from host-add and place it
   to dns.py to be used by both modules
 - Add support for "extra" per-type options
 - Hide DNS record part options in dnsrecord_find command as they
   have no effect for this command

https://fedorahosted.org/freeipa/ticket/2009

VERSION

@@ -79,4 +79,4 @@ IPA_DATA_VERSION=20100614120000
 #                                                      #
 ########################################################
 IPA_API_VERSION_MAJOR=2
-IPA_API_VERSION_MINOR=26
+IPA_API_VERSION_MINOR=27