Applied ticket 43 - clarified section 21.4.1 of 3315

Added that 'key ID' is 4 octet and that 'DHCP realm' is domain name and encoded as per section 8 of 3315.
Applied Ticket 54 - Added DUID-UUID and reference to RFC 6355
partial fix for http://wiki.tools.ietf.org/group/dhcpv6bis/ticket/88
Addressed issue #44 from the issue tracker.
Addressed issue #47 from the issue tracker
change delegating router to requesting router as detailed in: http://wiki.tools.ietf.org/group/dhcpv6bis/ticket/21
Merge branch 'master' of github.com:dhcwg/rfc3315bis
commit for http://wiki.tools.ietf.org/group/dhcpv6bis/ticket/88 not included .xml file
Addressed ticket #39 - specify minimal length for DUID.
Addressed ticket 40. Do not use the term sub-options.
Address #11 of Issue Tracker
Fixed ticket #90 in the issue traker
Address #56 of Issue Tracker, incorporated RFC6644
Fix two missed anchors in previous editing
Add the back-reference to 11.13 in the occurence where it looks most appropriate
Revert "Add the back-reference to 11.13 in the occurence where it looks most appropriate"

This reverts commit 921c504b71c7c5838043cf92ed5fa0165591caa9.
Additional patch for ticket #44, adding extra reference to section 22.13
Ticket 45: Using unspecified address to hint about valid/preferred lifetimes
Address ticket 87
Updated based on RFC3315bis XML changes.