[master] Update client code to RFC7550

Update the v6 client code to handle getting
IA_NAs and IA_PDs in the same request better.

Squashed commit of the following:

commit ad1bf23100eba541c26c6c26fc2c5c9dc57dd674
Author: Shawn Routhier <sar@isc.org>
Date:   Mon Nov 16 23:08:13 2015 -0800

    [rt40190] Use dhc6_check_status for addresses and prefixes

commit 4cb1d499342e68c5c93b7e8dac71c9adbd737846
Author: Shawn Routhier <sar@isc.org>
Date:   Mon Nov 16 22:02:05 2015 -0800

    [rt40190] Correct the tests for a status code in the client

    Some of the tests for the NoAddrs or NoPrefix codes in the
    were incorrect, checking for a return of not success instead
    of success.

commit 41ad9ea4438c0f64b95ec7afeac38afd2f3b36cb
Author: Shawn Routhier <sar@isc.org>
Date:   Fri Nov 13 21:04:55 2015 -0800

    [rt40190] Update site.h to have the correct default

commit cb720dac6670e1a6cc19b22550506ded4093abef
Author: Shawn Routhier <sar@isc.org>
Date:   Fri Nov 13 21:03:38 2015 -0800

    [rt40190] update per second set of review comments

    Mostly this is a set of updates to the documentation.
    The only code change is to add a backwards compatibility
    option in includes/site.h for people who want the old weightings
    for the client lease scoring.

commit 269a5324b950062380b4e3988f56593dc21d05d9
Author: Thomas Markwalder <tmark@isc.org>
Date:   Thu Nov 12 09:00:36 2015 -0500

    [40190] Fixed another typo

commit 7da158497cd9236c30dfdce2b115818d1954839f
Author: Thomas Markwalder <tmark@isc.org>
Date:   Thu Nov 12 07:29:33 2015 -0500

    [40190] Minor cosmetics in dhc6.c

commit a010737de36e5ad2f46bb11f471ac66ccbc856aa
Author: Shawn Routhier <sar@isc.org>
Date:   Sat Nov 7 00:05:20 2015 -0800

    [rt40190] Update the use of the minimum score

    Update the use of the minimum score to use #defines instead
    of 150.  This corrects it for the current values and allows
    us to change the values if we include a backwards compatibility
    option.

commit b078575da08c06a75a49110273bf42e24d03c08a
Author: Shawn Routhier <sar@isc.org>
Date:   Fri Nov 6 21:55:05 2015 -0800

    [rt40190] Updates per review comments

    Update several comments to be more informative

    The code changes are mostly to fold all the two
    bare_ia routines together.

commit 248c498d45db5533f992fb6eb30ee6c3c399ee81
Author: Shawn Routhier <sar@isc.org>
Date:   Tue Oct 20 02:06:45 2015 -0700

    [rt40190] Fix up some typos

commit ba074eff2e82af0cfd25428e7f38bccd5fef7241
Author: Shawn Routhier <sar@isc.org>
Date:   Tue Oct 20 01:28:34 2015 -0700

    [rt40190] Patch for client side of 7550

    Finish up the code to handle multiple PDs and NAs
    in a single request, this includes updating the
    command line to add the -R option to require the
    requested IAs rather than accept the best advertised
    offer.

commit 5bb4368b8410e3c7bcdc28fdf4ae5572df04d03b
Author: Shawn Routhier <sar@isc.org>
Date:   Thu Oct 15 09:50:14 2015 -0700

    [rt40190] checkpoint my work

    The basic code is working there are still some issues with how
    corner cases get handled that I need to resolve

commit 4c0dba90fcd71c85fca3612aa5083fa11645f8f6
Author: Shawn Routhier <sar@isc.org>
Date:   Sun Oct 11 19:23:53 2015 -0700

    [rt40190] Some changes for rfc7550, to be updated

    This is being checked in so I can look at other tickets
    but I plan to re-arrange the code a fair amount.

2 files changed, 8 insertions, 0 deletions

diff --git a/includes/dhcpd.h b/includes/dhcpd.h
index 02cdc5c0..1cf66d33 100644
--- a/includes/dhcpd.h
+++ b/includes/dhcpd.h
@@ -2863,6 +2863,7 @@ extern int nowait;
 extern int wanted_ia_na;
 extern int wanted_ia_ta;
 extern int wanted_ia_pd;
+extern int require_all_ias;
 
 extern const char *path_dhclient_conf;
 extern const char *path_dhclient_db;
diff --git a/includes/site.h b/includes/site.h
index ce7876ba..7c6d8431 100644
--- a/includes/site.h
+++ b/includes/site.h
@@ -298,6 +298,13 @@
    this option will be removed at some time. */
 /* #define INCLUDE_OLD_DHCP_ISC_ERROR_CODES */
 
+/* Use the older factors for scoring a lease in the v6 client code.
+   The new factors cause the client to choose more bindings (IAs)
+   over more addresse within a binding.  Most uses will get a
+   single address in a single binding and only get an adverstise
+   from a single server and there won't be a difference. */
+/* #define USE_ORIGINAL_CLIENT_LEASE_WEIGHTS */
+
 /* Include definitions for various options.  In general these
    should be left as is, but if you have already defined one
    of these and prefer your definition you can comment the