Merge pull request #1 from toreanderson/master

Some updates
Merge pull request #2 from toreanderson/master

As requested in e-mail...
Add discussion of ECMP and Appendix with survey of implementations
Add additional credits
Move paragraph to different section, and add 'cut here' node
Make the Security Considerations reflect the update to RFC6145
Miscellaneous edits..mostly improved the 'additional considerations' section
Add draft-ietf version
Add draft-ietf -01 version
Note that protocols built on SIIT are impacted

Make it clear that it is not only SIIT that is impacted by this draft,
but that it by extension impacts protocols that build on SIIT, such as
Stateful NAT64 (and probably MAP-T, but that's not spelled out).

Alberto Leiva made the observation that this was not clear - credit him
for doing so.