Allow overriding of SYSCONFDIR, LOCALSTATEDIR from recursor Makefile

Fixes #734.
Add tests for rfc2136 operation
Add RCodes for RFC2136

This adds the needed RCodes to support RFC2136 (YXDomain, NotZone and others)
Add useful comparison and methods to QType

These methods are used for rfc2136 to determine some requirements. The comparison operaters simply make it easy to compare things
in the code itself.

Some QTypes have been added because that's how RFC2136 defines them.
Add QClass NONE and ANY

RFC2136 uses NONE and ANY to check what type of operation to perform.
So, these QClasses are now added and registered as valid records.
Add hidesoaserial option to sdig

This options removes the soa-serial from sdig output. This is used because dyndns updates the serial, resulting in failing tests if we include it.
Add rfc2136 implementation basics

This commits adds a lot of files and code to implement rfc2136. The code was taken from a different branch and only added again.
There are still things missing.
Primary changes:
- Add rfc2136 methods to rfc2136handler.cc file and include file in build
- Add constructor for DNSResourceRecord to take a DNSRecord
- Add setContent and getZoneRepresentation to DNSResourceRecord for easy compare and set of content
  This removes the need to consantly check if it's an MX record, etc.
- Add compare operator to DNSResourceRecord to easily compare DNSResourceRecords
- Move SOA-EDIT calculation/changes to seperate method for re-use in rfc2136 code
- Move rfc1982LessThan to misc.hh for reuse
- Added code to handle update packets in questionOrRecurse
Add disable-rfc2136 and allow-2136-from options
Add rfc2136 statistics
Make sure rfc2136 packets are not cached.
Add option to purge a range out of packetcache.
Use new DNSResourceRecord constructor in resolver.
Add mastermake that understands QClass

This is needed to parse the update packages correctly which do have
records in other QClasses then just 'IN'.
We don't need it always, only for specific classes, which this mastermake tries to filter
This makes isc's dhcpd work with TSIG messages

Apperantly, isc's tsig code requires this to make pdns operate with dhcpd and tsig keys.
Add allow-2136-from and disable-rfc2136 options to start-test-stop
Remove fancy-records from start-test-stop
Actually use cachettl in start-test-stop
Add rfc2136handler to handle rfc2136 operation
Add rfc2136 implementation with replaceRRSEt and dirty cache clean

This completes the RFC2136 implementation and passes all the dyndns tests using the replaceRRSet method.

The runtest now understands a 'once' option because a SOA-update can only be performed once.
dnsbackend.hh has a listSubZone() - this is not a pretty method, but it's required to fix delegation flags without
reading the complete zone.
replaceRRSet is also updated to understand 'ANY' as a Qtype. This performs the query without the where type-cause. It also allows for not adding any items which makes it usable to delete RRSET's.
Remove non-needed check on rrset size