Update JSON Patch specs to the latest RFC 6902.

http://tools.ietf.org/html/rfc6902
Merge pull request #27 from seletskiy/json-patch-rfc-6902

Update JSON Patch specs to the latest RFC 6902
Deletions should not mandate a particular Accept header
Merge pull request #30 from celkins/excessive-delete-constraint

Deletions should not mandate a particular Accept header
Adding `extending` page and information.
Merge pull request #31 from json-api/extending

Adding `extending` page and information.
Notes section is really a Status section

* Rename the "Notes" section as "Status".
* Remove the emphasis from the entire section and
  place emphasis on the "work in progress" sentence.
* Call out that the spec is not stable.
* Rework paragraph about contributing.
* Tweak some grammar and punctuation (take the commas 
  from over here and push them over there -- Patrick).
Little typo fix
s/ID/URL

Btw, `a URL` or `an URL`?
Merge pull request #49 from RKushnir/patch-1

s/ID/URL
Merge pull request #48 from eoinoc/master

Little typo fix
Merge pull request #37 from reinh/patch-1

Notes section is really a Status section
Add note about content type.
No need to see 'extending' under see also on the extending page
Merge pull request #53 from gevious/master

Removed the extending link under 'see also' on the extending page
Fix media type for JSON patch.

We left off the +json

Fixes #42.
rels -> links.

Fixes #36.
Make note of PUT.

Fixes #4.
Singular resources are now wrapped with an array.

It's annoying to determine if something is singular or plural and then
process it. Much easier to make it always plural, and then see if the
length is one.

Fixes #8.
Add @steveklabnik and @wycats as editors.